I would like to thank several people whose guidance and support were invaluable ..... Particles Expand and Contract Rather than Intermolecular Distances Change . ...... Comprehension of almost every topic in chemistry to a great extent hinges on ...... ionic compounds, (e.g., NaCl, Table salt) the ball-and-stick models are ...
PROMOTING HIGH SCHOOL STUDENTS’ CONCEPTUAL UNDERSTANDINGS OF THE PARTICULATE NATURE OF MATTER THROUGH MULTIPLE REPRESENTATIONS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University
By Emine Adadan, M.A. ***** The Ohio State University 2006
Dissertation Committee: Approved by Professor Kathy C. Trundle, Advisor
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Professor Karen E. Irving, Co-Advisor
________________________ Advisor and Co-Advisor
Professor Patricia A. Brosnan College of Education and Human Ecology
Copyright Emine Adadan 2006
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ABSTRACT
This study mainly explored the efficacy of the two instructional interventions, namely Reform-Based Teaching with Multiple Representations (RBTw/MR) and Reform-Based Teaching (RBT) on stimulating change in students’ conceptual understandings of the particulate nature of matter (PNM) and maintaining those scientific understandings constructed during the instruction over a three-month period. In this context, this study also examined the RBTw/MR and RBT group students’ types of conceptual understandings of the PNM before, immediately after and three-months after the interventions and described the patterns of individual students’ conceptual pathways during the course of the study. In addition, this study looked into the variation in the RBTw/MR and RBT students’ understandings of each constituent concept of the PNM in the three states of matter from the pre to the post to the delayed posttest. This study was conducted in two introductory level chemistry classes of a suburban high school. The participants of the study included a total of 42 students who were enrolled in one of the two classes of the chemistry teacher who taught both of the classes. Both the RBTw/MR and the RBT group students were engaged in the same activities with the same sequence of experiences such as compression of solids, liquids and gases, melting of solids and evaporation of liquids. However, the RBTw/MR
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instruction differed from the RBT instruction in terms of the frequency of using the multiple representations in relationship to the macroscopic phenomenon and the likely actions that occur at the submicroscopic level. Although the RBTw/MR instruction integrated the pedagogies of inquiry, written and oral discourse, and multiple representations, the RBT instruction lacked the multiple representations component by not using visual submicroscopic representations with the students in this group. A quasi-experimental control group research design with a pretest, posttest, and delayed posttest was employed by incorporating qualitative data collection and analysis methods. In order to assess students’ conceptual understanding of the PNM, the openended questionnaire, namely Nature of Matter Diagnostic Questions, was administered to both groups just before, immediately after and three months after the instructional interventions. Fifteen of the 42 students were also interviewed following the posttest. Additional data sources included videotaping of teacher-student conversations, field notes, and student artifacts (e.g., journal writings, activity sheets). The results of the study revealed the positive short- and long-term learning impacts on the RBTw/MR group students’ conceptual understandings of the PNM. Before the instruction, a majority of students in both groups (82.6%, RBTw/MR; 73.7%, RBT) held scientific types of conceptual understandings of the PNM, which included alternative with scientific fragments, alternative fragments or no understanding. Similarly, the Wilcoxon-Mann-Whitney test resulted in no significant difference between the groups in terms of understanding the aspects of the PNM prior to any instruction.
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Immediately following the instruction, 52.1% of the RBTw/MR students held the types of conceptual understandings of either scientific or scientific fragments. However, only 31.6% of the RBT students exhibited the conceptual understanding of scientific with alternative fragments, which indicates weak conceptual changes. The results of the Wilcoxon-Mann-Whitney test conducted on students’ post-NMDQ scores showed that the RBTw/MR group students developed a significantly greater number of scientific conceptual understandings of the PNM compared to the RBT students. Three months after the instruction, 34.8% of the RBTw/MR group students held onto their scientific conceptual understandings of the PNM, only 15.8% of the RBT students’ conceptual understandings of the PNM differed from their initial type of conceptual understandings. The results of the Wilcoxon-Mann-Whitney test performed on students’ delayed-NMDQ scores revealed that the RBTw/MR group students maintained their scientific understandings over a three-month period. The change in the RBTw/MR students’ conceptual understandings of the PNM ranged from no progress to radical progress, whereas the RBT students only showed slight progress toward a scientific understanding of the PNM shortly after the instruction. Over a three month period, although the patterns in the durability of both groups of students’ conceptual understandings of the PNM changed between stable and full decay, the RBTw/MR group students were more likely to hold onto their scientific understandings of the PNM.
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Dedicated to my family: my mother, Remziye; my father, Ismet; my sister, Emel, and my brother, Erdoğan
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ACKNOWLEDGMENTS I would like to thank several people whose guidance and support were invaluable in the completion of this dissertation. First, I would like to express my sincere appreciation to Dr. Kathy C. Trundle, my advisor, for her constant encouragement during the difficult times of this research project. I am grateful to her for working with me each and every phase of this project, carefully reading the early drafts of this dissertation, regularly meeting with me to discuss my progress on this project, offering insightful feedback, and challenging my thinking, which helped me turn my vague ideas into a coherent whole. I am also deeply indebted to my co-advisor Dr. Karen E. Irving for her sustained support in many ways throughout this project. I am thankful to Dr. Irving for helping me with the design of the instructional interventions and the development of the assessment instruments, providing effective feedback and having long and insightful conversations with me about every chapter of this dissertation, which inspired me to think critically. I wish to express my gratitude to Dr. Patricia A. Brosnan for her generous support, careful consideration of my ideas and invaluable suggestions for the improvement of my dissertation. I also would like to extend my appreciation to Dr. Michael E. Beeth, my previous advisor, whose initial assistance in my doctoral study planted the seed of this research.
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My special thanks go to Ms. B. who generously opened her classes to implement the instructional interventions in her classes. Without her willingness and hard work during the implementation of the the instructional interventions, this study would not have been possible. No amount of thanks can express my thankfulness to the participants of this study. I am extremely indebted to the participants of this study for their patience, effort and cooperation. Without their active involvement, this study would not have been possible. Many thanks go to Funda and Sedat for their help with the re-coding of the data. I also wish to thank Ayse, Behzat, Bengu, Duygu, Elif, Elvan, Figen, Rifat, Funda, Gonul, Huban, Hakan, Pelin and Sedat for their sincere friendship and support in many ways during my time at the Ohio State. I would like to extend my gratitude to my international friends Diana and Michael, Kim and Greg, Tzu-Ling and Shanu for their genuine friendship and making me feel the warmth of a family when I am away from home. I am so glad that I have met each and every one of you. I also would like to thank my parents Remziye and Ismet, my sister Emel, my brother Erdogan for their special love and unconditional support. Thanks for believing in me, encouraging me to pursue my goals and sharing both the good times and the bad. Words can never express how much I appreciate all that you have done for me. My deep gratitude goes to Turkish Ministry of Education for providing me the scholarship and the opportunity to pursue my graduate studies at the Ohio State University.
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VITA September 6, 1973……………………………………...Born – Edirne, Turkey 1995…………………………………………………….B.S., Chemistry Education, Marmara University, Istanbul, Turkey 1995 – 1999..…………………………………………...Chemistry Teacher Özel Yeni Dünya High School Istanbul, Turkey 2002…………………………………………………….M.A. Science Education The Ohio State University Columbus, Ohio 2002 – present..………………………………………....Ph.D. Student, Science Education The Ohio State University Columbus, Ohio PUBLICATIONS 1. Beeth, M. E., Adadan, E., Firat, G. G., & Kutay, H. (2003). The Changing Face of Bio 101 with Regard to Nation’s Science Standards. St Louis, MO: Annual meeting of Association for the Educators of the Teachers of Science. (ERIC Document Reproduction Service No. ED474716). 2. Beeth, M. E. & Adadan, E. (2006). The influences of university-based coursework on field experience. Journal of Science Teacher Education, 17(2), 103-120.
FIELDS OF STUDY Major Field: Education Specialization: Science Education viii
TABLE OF CONTENTS Page Abstract ............................................................................................................................... ii Dedication…………………………………………………………………………………v Acknowledgments.............................................................................................................. vi Vita................................................................................................................................... viii List of Tables .................................................................................................................. xiii List of Figures .................................................................................................................. xvi CHAPTERS 1. INTRODUCTION .......................................................................................................... 1 The Particulate Nature of Matter in Science Education Standards................................. 4 Rationale for the Study ................................................................................................... 6 Purpose of the Study ..................................................................................................... 10 Research Questions....................................................................................................... 11 Significance of the Study .............................................................................................. 12 Definition of Terms....................................................................................................... 13 2. LITERATURE REVIEW ............................................................................................. 15 Introduction................................................................................................................... 15 Constructivism .............................................................................................................. 16 Individual Constructivism...................................................................................... 17 Social Constructivism ............................................................................................ 18 Conceptual Change Learning........................................................................................ 20 The Conceptual Change Learning in Science Education....................................... 21 The Conceptual Change Learning in Cognitive-Developmental Psychology ....... 27 Summary ................................................................................................................ 30 Metacognition and Intentional Conceptual Change...................................................... 31 Students’ Alternative Conceptions of the Particulate Nature of Matter ....................... 33 Matter is Continuous.............................................................................................. 35 Attributing Macroscopic Properties of Matter to its Particles ............................... 36 Matter is Mostly Static........................................................................................... 38 Existence of some Materials between Particles ..................................................... 39 Alternative Understandings Concerning the Relative Spacing of Particles........... 41 Alternative Understandings Concerning the Existing Forces between Particles... 42 Particles Expand and Contract Rather than Intermolecular Distances Change ..... 42 ix
Instructional Approaches to Address Students’ Alternative Conceptions of the PNM 43 Summary ................................................................................................................ 52 Teaching with Multiple Representations ...................................................................... 62 Dual Coding Theory .............................................................................................. 64 Cognitive Theory of Multimedia Learning............................................................ 66 Cognitive Load Theory .......................................................................................... 67 Research on Multi-Representational Learning ...................................................... 69 Computer-Based Multimedia........................................................................... 69 Student-Generated Drawings ........................................................................... 74 Conclusion .................................................................................................................... 77 3. METHODS AND PROCEDURES............................................................................... 79 Introduction................................................................................................................... 79 The Pilot Study ............................................................................................................. 80 Research Design............................................................................................................ 83 Participants and Context of the Study........................................................................... 84 The Framework of the Instructional Interventions ....................................................... 86 Data Collection and Recording Procedures .................................................................. 93 Open-ended Questionnaire..................................................................................... 94 Student Interviews ................................................................................................. 96 Student Artifacts .................................................................................................... 97 Videotaped Classroom Conversations ................................................................... 99 Field Notes ............................................................................................................. 99 Data Analysis .............................................................................................................. 100 Qualitative Analysis............................................................................................. 100 Trustworthiness of the Study ............................................................................... 104 Member Checking.......................................................................................... 105 Prolonged Engagement .................................................................................. 105 Inter-rater Reliability ..................................................................................... 105 Quantitative Analysis........................................................................................... 106 Validity Issues of the Quasi-Experimental Study................................................ 109 Selection......................................................................................................... 109 History............................................................................................................ 110 Maturation...................................................................................................... 110 Mortality ........................................................................................................ 111 Instrumentation and Testing .......................................................................... 111
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4. ANALYSIS OF DATA............................................................................................... 121 The RBTw/MR Group Students’ Conceptual Understandings of the PNM............... 122 Types of Conceptual Understanding Categories.................................................. 122 Before the RBTw/MR Intervention ..................................................................... 122 After the RBTw/MR Intervention........................................................................ 126 Three-Months after the RBTw/MR Intervention................................................. 129 Summary .............................................................................................................. 131 The RBTw/MR Group Students’ Conceptual Pathways of the PNM.................. 132 Conceptual pathway 1: Radical progress and either stability or a slight decay ……………………………………………………………………………….133 Conceptual pathway 2: Radical progress with a moderate decay.................. 138 Conceptual pathway 3: Moderate progress and stable................................... 142 Conceptual pathway 4: Moderate progress with a full decay ........................ 144 Conceptual pathway 5: Slight progress and stable ........................................ 146 Conceptual pathway 6: Slight progress with a slight decay .......................... 151 Conceptual pathway 7: Slight progress with a full decay.............................. 153 Conceptual pathway 8: Stable with slight progress ....................................... 156 Conceptual pathway 9: No progress .............................................................. 157 Summary .............................................................................................................. 159 The RBT Group Students’ Conceptual Understandings of the PNM ......................... 160 Before the RBT Intervention ............................................................................... 160 After the RBT Intervention.................................................................................. 162 Three-Months after the RBT Intervention ........................................................... 165 Summary .............................................................................................................. 167 The RBT Group Students’ Conceptual Pathways of the PNM............................ 167 Conceptual pathway 5: Slight progress and stable ........................................ 168 Conceptual pathway 7: Slight progress with a full decay.............................. 172 Conceptual pathway 9: No progress .............................................................. 175 Summary .............................................................................................................. 181 Comparison of the RBTw/MR and the RBT Group’s Conceptual Understandings... 182 Based on Descriptive Analysis ............................................................................ 182 Based on Statistical Analysis ............................................................................... 188 Students’ Conceptual Understandings of the Scientific Aspects of the PNM ............ 197 Matter as Discrete Particles ................................................................................. 197 The Arrangement of the Particles ........................................................................ 202 The Relative Spacing between the Particles ........................................................ 206 The Motion of the Particles.................................................................................. 209 The Existence of Attraction Forces between the Particles................................... 213
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The Existence of a Vacuum between the Particles .............................................. 216 Summary .............................................................................................................. 222 Conclusion .................................................................................................................. 222 5. DISCUSSION ............................................................................................................. 224 Introduction................................................................................................................. 224 Students’ Types of Conceptual Understandings of the PNM ..................................... 224 The Nature of Students’ Conceptual Pathways of the PNM....................................... 235 Students’ Conceptual Understandings of the Scientific Aspects of the PNM ............ 245 6. IMPLICATIONS ........................................................................................................ 251 Introduction................................................................................................................. 251 Implications for Instruction......................................................................................... 252 Implications for Teacher Education............................................................................ 255 Implications for Educational Research ....................................................................... 256 Limitations of the Study.............................................................................................. 259 Suggestions for Further Research ............................................................................... 261 APPENDICES Appendix A: Description of instructional interventions................................................. 265 Appendix B: Student activity sheets ............................................................................... 283 Appendix C: Nature of matter diagnostic questions and answer key ............................. 306 Appendix D: Concent forms and letters.......................................................................... 333 LIST OF REFERENCES................................................................................................ 338
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LIST OF TABLES Table
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1.1: The scientific aspects vs. students' alternative conceptions of the PNM..................... 9 2.1: Summary of studies that examined students’ conceptions of the PNM with or without specific instruction. ................................................................................................... 55 3.1: Demographics of the RBTw/MR and the RBT groups.............................................. 85 3.2: The instructional strategies implemented in RBTw/MR and RBT groups................ 91 3.3: Meaning of the codes............................................................................................... 116 3.4: Types of Conceptual Understandings and Criteria. ................................................. 118 3.5: Coding Sheet 2......................................................................................................... 120 4.1: Students’ types of conceptual understandings prior to the RBTw/MR. .................. 123 4.2: Summary of conceptual understandings for the RBTw/MR group. ........................ 125 4.3: Students’ types of conceptual understandings shortly after the RBTw/MR............ 127 4.4: Students’ types of conceptual understandings three-months after the RBTw/MR.. 129 4.5: Summary of the identified conceptual pathways for each group............................. 133 4.6: Conceptual pathway 1 within the RBTw/MR group (Students 12m, 16m, 17m, 22m). ................................................................................................................................. 134 4.7: Conceptual pathway 2 within the RBTw/MR group (Students 3m, 5m, 9m). ........ 138 4.8: Conceptual pathway 3 within the RBTw/MR group (Students 1m, 2m, 6m, 11m). 143 4.9: Conceptual pathway 4 within the RBTw/MR group (Student 21m). ...................... 145
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4.10: Conceptual pathway 5 within the RBTw/MR group (Students 4m, 7m, 8m, 13m, 14m, 15m). .............................................................................................................. 147 4.11: Conceptual pathway 6 within the RBTw/MR group (Student 18m). .................... 152 4.12: Conceptual pathway 7 within the RBTw/MR group (Student 20m, 23m). ........... 154 4.13: Conceptual pathway 8 within the RBTw/MR group (Student 10m). .................... 156 4.14: Conceptual pathway 9 within the RBTw/MR group (Student 19m). .................... 158 4.15: Students’ types of conceptual understandings before the RBT. ............................ 160 4.16: Summary of conceptual understandings for the RBT group. ................................ 162 4.17: Students’ types of conceptual understandings shortly after the RBT.................... 164 4.18: Students’ types of conceptual understandings three-months after the RBT.......... 166 4.19: Conceptual pathway 5 within the RBT group (number 3, 4, 8, 12)....................... 168 4.20: Conceptual pathway 7 within the RBT group (numbers 2, 6, 10). ........................ 173 4.21: Conceptual pathway 9 within the RBT group (Sci.w/Alt.Frag, numbers 5, 13 14, 16, 18; Alt. w/Sci.Frag., numbers 7, 11, 15, 17, 19; Alternative Frag., numbers 1, 9). 176 4.22: Summary of the RBTw/MR and the RBT group students’ types of conceptual understandings of the PNM. ................................................................................... 183 4.23: The Sign Test Statistics for changes in students’ types of conceptual understandings after the instructional interventions. ....................................................................... 189 4.24: The Sign Test statistics for changes in students’ types of conceptual understandings three-months after the instructional interventions. ................................................. 191 4.25: The Wilcoxon-Mann-Whitney Test on students’ pretest scores............................ 193 4.26: The Wilcoxon-Mann-Whitney Test on students’ posttest scores. ......................... 194
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4.27: The Wilcoxon-Mann-Whitney Test on students’ delayed posttest scores............. 195 4.28: The percentages of the RBTw/MR group students’ types of conceptual understandings of the discrete nature of matter. ..................................................... 198 4.29: The percentages of the RBT group students’ types of conceptual understandings of the discrete nature of matter.................................................................................... 200 4.30: The percentages of the RBTw/MR group students’ types of conceptual understandings of the arrangement of particles. ..................................................... 202 4.31: The percentages of the RBT group students’ types of conceptual understandings of the arrangement of particles.................................................................................... 205 4.32: The percentages of the RBTw/MR group students’ types of conceptual understandings of the spacing between particles of matter. ................................... 207 4.33: The percentages of the RBT group students’ types of conceptual understandings of the spacing between particles of matter. ................................................................. 208 4.34: The percentages of the RBTw/MR group students’ types of conceptual understandings of the motion of particles............................................................... 211 4.35: The percentages of the RBT group students’ types of conceptual understandings of the motion of particles. ........................................................................................... 212 4.36: The percentages of the RBTw/MR group students’ types of conceptual understandings of the forces that exist between the particles of matter. ................ 214 4.37: The percentages of the RBT group students’ types of conceptual understandings of the forces that exist between the particles............................................................... 216 4.38: The percentages of the RBTw/MR group students’ types of conceptual understandings of the existence of nothing between the particles of matter. ......... 218 4.39: The percentages of the RBT group students’ types of conceptual understandings of the existence of nothing between the particles of matter........................................ 221
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LIST OF FIGURES Figure
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2.1: The closed flask after some of the gas was taken out (Scott, 1992, p.208). .............. 39 2.2: Molecules in a liquid: A textbook illustration (Andersson, 1990). ........................... 41 2.3: The task of gaseous diffusion (Meheut & Chomat, 1990, p.275).............................. 45 2.4: The task of comparison of three states of matter at the particulate level (Meheut & Chomat, 1990, p.277)................................................................................................ 46 2.5: The change of state (solid-gas) task (Meheut & Chomat, 1990, p.278). ................... 46 2.6: The task involves the distances between particles (Scott, 1992, p.209).................... 49 2.7: Abstraction continuum (Pozzer & Roth, 2003). ........................................................ 63 3.1: Dissolving of a salt ................................................................................................... 89 3.2: Motion of particles in three states of matter (Available at http://www.chem.purdue.edu/gchelp/atoms/states.html).......................................... 89 3.3: Coding Sheet 1......................................................................................................... 116 4.1: Drawings that represent the student 12m’s conceptions of the arrangement of particles in the three states of matter....................................................................... 136 4.2: Drawings that represent student 22m’s conceptions of melting of a solid. ............. 137 4.3: Drawings that represent student 9m’s conceptions of the uniform distribution of gases........................................................................................................................ 140 4.4: Drawings that represent student 9m’s conceptions of the relative spacing between the particles in the three states of matter....................................................................... 140 4.5: Drawings that represent student 1m’s conceptions of the relative spacing between the particles in the three states of matter....................................................................... 144 xvi
4.6: Drawings that represent student 21m’s conceptions of the relative spacing between the particles of liquids............................................................................................. 146 4.7: Drawings that represent student 4m’s conceptions of the arrangement of solid particles. .................................................................................................................. 147 4.8: Drawings that represent two of the RBTw/MR students’ conceptions of the relative spacing between the particles on the posttest. ........................................................ 148 4.9: Drawing that represent two of the RBTw/MR students’ conceptions of the relative spacing between the particles on the delayed posttest. ........................................... 149 4.10: Drawings that represent student 15m’s alternative conceptions of the mixture of food coloring and water molecules at the submicroscopic level ............................ 150 4.11: Drawings that represent student 7m’s conceptions of the change in size of the particles in the three states of matter....................................................................... 151 4.12: Drawings that represent student 18m’s conceptions of the discrete nature of matter in the three states of matter. .................................................................................... 153 4.13: Drawings that represent student 23m’s conceptions of condensation of a gas...... 155 4.14: Drawings that represent student 10m’s conceptions of the existence of bonds between the particles of liquids and solids. ............................................................ 157 4.15: Drawings that represent student 19m’s conceptions of the discrete nature of matter. ................................................................................................................................. 159 4.16: Drawings that represent student 3’s conceptions of the discrete nature of matter in the three physical states on the posttest. ................................................................. 170 4.17: The crystal lattice structure of the salt (Tocci & Viehland, 1996, p.159). ............ 170 4.18: Drawings that represent student 3’s conceptions of the discrete nature of matter in the three physical states on the delayed posttest..................................................... 171 4.19: Drawings that represent student 6’s conceptions of the discrete nature of matter in the three physical states. ......................................................................................... 173 xvii
4.20: Drawings that represent student 6’s conceptions of the spacing between the particles on the posttest........................................................................................... 175 4.21: Drawing that represent student 6’s conception of condensation of a gas on the delayed posttest....................................................................................................... 175 4.22: Drawings that represent student 14’s conceptions of the discrete nature of matter on the pretest. ............................................................................................................... 177 4.23: Drawings that represent student 14’s conceptions of the discrete nature of matter on the posttest. ............................................................................................................. 179 4.24: Drawings that represent the student 14’s conceptions of condensation of a gas and melting of a solid on the posttest. ........................................................................... 179 4.25: Drawings that represent student 14’s conceptions of the discrete nature of matter on the delayed posttest. ................................................................................................ 180 4.26: Drawings that represent student 14’s conceptions of condensation of a gas and melting of a solid on the delayed posttest............................................................... 181 4.27: The overall trends in the RBTw/MR group students’ conceptual pathways of the PNM........................................................................................................................ 184 4.28: The overall trends in the RBT group Students’ Conceptual Pathways of the PNM. ................................................................................................................................. 186 4.29: Median of types of conceptual understanding scores of the RBTw/MR and the RBT group ....................................................................................................................... 192 4.30: Example of drawings that show the RBTw/MR students' conceptions of the discrete nature of matter. ...................................................................................................... 198 4.31: Examples of drawings that show the RBT students’ conceptions of the discrete nature of matter. ...................................................................................................... 201 4.32: Drawings that represent the two RBTw/MR students’ alternative conceptions of the arrangement of liquid particles. .............................................................................. 203
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4.33: Drawings that represent student 18’s conceptions of the spacing between particles in the three states of matter. .................................................................................... 209 4.34: Drawings that represent student 13m’s alternative conceptions of the diffusion of gases........................................................................................................................ 211 4.35: Drawing that represent student 13m’s alternative conception of the existence of a vacuum between the particles. ................................................................................ 220 4.36: Drawing that represent student 16’s alternative conception of the existence of a vacuum between the particles of liquids................................................................. 221 5.1: Particles in continuous matter (Tocci & Viehland, 1996, p.IV) .............................. 249
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CHAPTER 1 INTRODUCTION If … all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generation, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis, … that all things are made of atoms – little particles that move around in perpetual motion, attracting … [or] repelling … one another. In that one sentence, you will see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied (Feynman, 1995, p.4). In Six Easy Pieces, the well-known physicist, Richard P. Feynman (1995) places the particulate nature of matter, as stated in part above, at the heart of the scientific enterprise. Scientific endeavors are mainly invested in describing the natural world, which is, at some level, the composition of solid, liquid, and gaseous substances. The characteristics of these substances are substantially associated with the structure and behavior of particles of which they are made. Understanding the nature and behavior of matter is not only essential for scientists but also for students as they are called to be scientifically literate citizens of the society in an information age. Thus, students are expected to be familiar with the rituals of scientific inquiry and interested in how and why various natural phenomena take place in everyday life. The dissolving of sugar in a cup of tea, the apparent disappearance of water after raining, and the expansion and the contraction of power lines with the change in weather conditions are some occurrences of daily life, but few people relate the basis of such phenomena to the nature of matter.
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Feynman (1995) was extremely optimistic in considering that an individual just needs a little imagination and thinking to recognize the paramount function of the particulate nature of matter (PNM). However, students experience a very hard time in learning the counterintuitive idea of the discontinuity of matter, because this idea competes with what students observe in real life—what they see is a drop of water, which is smooth and continuous. Therefore, they usually resist accepting the idea that a drop of water consists of a large number of particles that are attracted to one another and are constantly in motion. Both the idea of the discontinuity of matter and all other chemical activity are not accessible through direct observations. Unlike many other sciences, understanding of chemistry is, for the most part, based upon making sense of unobservable and untouchable phenomena. Research in science education suggests that due to the abstract nature of chemistry, students at all grade levels fail to conceptually understand the core concepts in chemistry even following the formal chemistry instruction (Ben-Zvi, Eylon, & Silberstein, 1987; Gabel, 1998; Hesse & Anderson, 1992; Krajcik, 1991; Nakhleh, 1992; Osborne & Cosgrove, 1983). Typically, the major difficulty arises in the area of understanding macroscopic changes such as color change or formation of precipitates as a particulate action (Ben-Zvi et al., 1987; Gabel, 1998; Harrison & Treagust, 2001; Solsona, Izquierdo, & Jong, 2003). Knowledge in chemistry is inherently communicated through representations— symbols, equations, formulas, molecular structure diagrams, three-dimensional models and so on (Hoffmann & Laszlo, 1991). Accordingly, the teaching and learning of chemistry requires three levels of representation, namely, macroscopic (sensory), atomic/molecular (submicroscopic) and symbolic (formulae and algorithms) (Gabel, 2
1993, 1998; Johnstone, 1982). At the macroscopic level, chemistry is observable, (e.g., rusting of iron). At the submicroscopic level, the chemical phenomenon, where iron atoms combine with oxygen molecules in the air to produce ferrous oxide, is unavailable to direct observation. In order to represent this phenomenon at the symbolic level, a chemical equation with chemical symbols and numbers is needed, [e.g., 2 Fe(s) + O2(g)
2 FeO(s)]. The National Science Education Standards
(National Research Council [NRC], 1996) recognize the important role of three levels of representations in chemistry and require students, particularly in grades 9 to 12, to be able to move back and forth among three levels of representations in a meaningful way to develop the understanding of the nature and behavior of matter. In practice, however, “chemistry teaching emphasizes the symbolic level and problem-solving at the expense of the phenomena and particle levels” (Gabel, 1993; p.193). That is, teaching chemistry by means of symbols and numbers to express invisible phenomenon makes the situation even more complicated and does not effectively serve long-lasting learning of basic concepts in chemistry (Gabel, 1993). Science educators should notice that understanding the fundamental aspects of the PNM lays the foundation to explain observable changes as submicroscopic activities, which ultimately promotes a scientific understanding of basic chemistry concepts (Nakhleh, 1992). Snir, Raz, and Smith (2003) claimed that it is critical to help students develop a comprehensive understanding of the notion of the PNM, because “their [students’] failure to learn the particulate model will impair their learning of science in subsequent years” (p. 796).
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The Particulate Nature of Matter in Science Education Standards The nature and behavior of matter as a fundamental topic of science curricula takes its essential place in the USA’s school science standards (American Association for the Advancement of Science (AAAS), 1993; National Research Council [NRC], 1996). The physical science content standards in both the National Science Education Standards (NSES) and the Benchmarks for Science Literacy propose addressing the diverse aspects of the PNM in every grade level with varying depth and breadth. In the early grades (K-4), students are curious about nature and highly motivated to explore their environment by observing and manipulating available materials. For these early elementary school children, the physical science content standards in the NSES expect them to construct an understanding of the macroscopic properties of objects and materials that they encounter in daily life. By the end of grade 4, students are supposed to be able to describe and classify objects by relying on their extensive properties (that change with respect to the amount of objects), make distinctions between the objects considering the type of substance of which they are made, and distinguish the characteristics of three states of matter. The Benchmarks for Science Literacy (AAAS, 1993), however, suggest that students by the end of grade 5 should construct the following concepts: conservation of mass, physical states of matter, the notion of the discontinuity of matter without labeling the particles as atoms or molecules, and of chemical change. Compared to the Standards (NRC, 1996), the Benchmarks (AAAS, 1993) seem demanding in terms of including several aspects of the nature of matter with extensive coverage in the early years of education.
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Considering the foundational prior knowledge that students are supposed to build in the preceding years, they are assumed to be ready for dealing with the aspects of the nature and behavior of matter more in depth in grades 5 to 8. Consequently, the physical science content standards in the NSES expect students in grades 5-8 to explore the intensive properties of the substances such as a boiling point, solubility, density, and chemical reactions but not at the particulate level. In contrast, the Benchmarks for Science Literacy require students in grades 5-8 to develop an understanding of atoms, molecules, and the intrinsic motion of atoms and molecules, and to make a distinction in three states of matter with regard to the motion of particles as well as explaining the concept of conservation of mass considering the number of particles. Based upon cognitive developmental research (Piaget, 1970), students in grades 9-12 are considered to be competent enough to use their cognitive and manipulative skills to understand advanced abstract scientific concepts. In this regard, the physical science content standards in the NSES, for the first time, urge using the term atom instead of the term particle to refer to building blocks of matter. Both the National Science Education Standards and the Benchmarks for Science Literacy recommend teaching and learning of the structure of a single atom in grades 9-12. In doing so, students are expected to relate macroscopic properties of matter to the structure of the matter. The content for grades 9-12 in both documents, in fact, implicitly refers to the key aspects of the PNM, which include the following: 1) the relative spacing between the particles, 2) the forces of attraction between the particles, 3) the nature of particles themselves (the structure of an atom), and 4) the intrinsic motion of the particles.
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Rationale for the Study The contemporary views of learning (Piaget, 1970; Vygotsky, 1978) are structured around the tenets of a constructivist philosophy, which primarily focuses on how people come to know. Therefore, understanding the processes of knowing is a major concern in order to explain the ways of human knowledge construction. The constructivist epistemology views knowledge as being constructed in such a way as scientists typically build their new theories on previously established scientific theories or models within the norms of normal science (Kuhn, 1996). Accordingly, students are also capable of actively utilizing their prior knowledge to make sense of unfamiliar ideas introduced in the science classes. Researchers have claimed that the prior knowledge that students bring to the classroom has a considerable impact on their subsequent learning (Duit & Treagust, 1995, 1998, 2003). In the last couple of decades, research into learning in science has documented students' conceptions of scientific phenomena either prior to or following instruction (Driver, Squires, & Wood-Robinson, 1994; Duit, 2006). These research reports have drawn attention to the issue that students' conceptions of natural phenomena are sometimes inconsistent with the commonly accepted scientific knowledge, and usually resistant to change even following the instruction. Driver and Easley (1978) called the conceptions that divert from scientific views as alternative frameworks, articulating the fact that in “learning about the physical world, alternative interpretations seem to be the product of pupil's imaginative efforts to explain events and abstract communalities they see between them” (p.62).
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In contrast to other science concepts such as motion, students’ understanding of the particulate nature of matter is intrinsically restricted to their perceptual experiences from daily life. Students can be familiar with atoms and molecules from popular media— television programs or books (Johnston, 1990), because the stylized atoms are commonly used as a logo for TV programs or in the front cover of books. It does not seem plausible that students could intuitively perceive the phenomenon that matter is made of discrete particles before they are introduced to these ideas in school. In this respect, Sequeira and Leite (1990) argued that before any instruction, students either do not hold preexisting knowledge of the PNM or are unsure about how to use the particle ideas in their explanations of the given phenomena. The research into students’ conceptions of the PNM showed that students in every grade level easily develop either spontaneous or instruction induced alternative conceptions about the PNM (Ben-Zvi, Eylon, & Silberstein, 1986; Griffiths & Preston, 1992; Johnson, 1998c; Johnston, 1990; Lee, Eichinger, Anderson, Berkheimer, & Blakeslee, 1993; Nakhleh & Samarapungavan, 1999; Nakhleh, Samarapungavan, & Saglam, 2005; Novick & Nussbaum, 1981; Pereira & Pestana, 1991; Pozo & Gómez-Crespo, 2005; Scott, 1992; Sequeira & Leite, 1990; Snir et al., 2003; Tsai, 1999). The scientific aspects and the characteristics of students’ typical alternative conceptions of the PNM are compared in Table 1.1 (see p. 9). The research into students’ alternative conceptions in science calls for the need to develop effective instructional interventions to facilitate the construction of scientific views of the natural phenomena among students (Duit & Treagust, 2003). There are extensive reviews of literature on the type of conceptual change pedagogies adopted by researchers to move students’ toward school science views in different domains of 7
science (Basili & Sanford, 1991; Guzetti, Snyder, Glass, & Gamas, 1993; Scott, Asoko, & Driver, 1992). Specifically, to promote change in students' conceptions of the PNM, researchers have implemented such teaching pedagogies as inquiry-based learning (Singer, Tal, & Wu, 2003), discrepant events (Nussbaum & Novick, 1982), (social) constructivist pedagogies (Johnson, 1998c; Kabapinar, Leach, & Scott, 2004), analogies (Tsai, 1999), concrete models (Harrison & Treagust, 2000) and visual tools/multiple representations (Bunce & Gabel, 2002; Rohr & Reimann, 1998; Snir et al., 2003; Tasker & Dalton, 2006; Williamson & Abraham, 1995). In recent years, using visual tools such as static or computer animated molecular models accompanied with oral and written discourse gained prominence and was acknowledged to be promising in the construction of scientific conceptions (Ardac & Akaygun, 2004, 2005; Barnea & Dori, 1999; Snir et al., 2003; Williamson & Abraham, 1995). However, the available research that used multiple representations as an instructional pedagogy for teaching the aspects of the PNM is limited in quantity (Bunce & Gabel, 2002; Rohr & Reimann, 1998; Snir et al., 2003; Tasker & Dalton, 2006; Williamson & Abraham, 1995). The pertinent research either entailed small-scale qualitative studies or just provided statistical evidence of learning benefits across different classroom contexts. Therefore, there is still a need for research, particularly mixed method studies that focus on addressing how multiple representations serve students’ learning of the aspects of the PNM by seeking both quantitative and qualitative evidence in learning outcomes. Van Meter and Garner (2005) identified a lack of research into learner-generated drawings as a multi-representational teaching pedagogy, and how this particular pedagogy supports student learning of scientific concepts still remains 8
unexplored. In this respect, there is a need for research to identify the impact of learnergenerated drawings as to the short- and long-term outcomes of student learning in science.
Scientific Conceptions
Alternative Conceptions
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Matter is made up of particles.
• Matter is continuous.
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Particles are in continuous motion/or vibration in all three states of matter.
• Particles are static, particularly in the solid state.
•
Nothing exists between the particles of matter.
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The distances between particles of a solid and a liquid are similar.
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The attraction forces exist between the particles of matter.
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The macroscopic properties of matter are collective properties of the particles and cannot be attributed to a single particle.
• Students usually believe in the existence of air (or some other material) between the particles of matter. • Students’ particle model drawings usually show the spacing for the liquid state as intermediate between the solid and gas state. • Students usually relate the existence of attraction forces (intermolecular forces) between the particles to the concept of chemical bonding. • Students tend to attribute observable properties of matter such as color, hardness, hotness/coldness, smell, shape, and physical state to its subsubmicroscopic particles.
Table 1.1: The scientific aspects vs. students' alternative conceptions of the PNM.
Moreover, teachers frequently encounter problems with the short duration of newly constructed scientific conceptions. Georghiades (2000) introduced the term durability as an answer to the question of “How long does a conception remain in effect, within the learners cognitive repertoire?” (p.124). He asserted that students’ newly 9
established scientific personal theories may display regression (conceptual decay) to initial conceptions (alternative conceptions) after a period of time. Consistent with the conceptual change theory of learning, the durability of new conceptions is considered to be critical to the construction of subsequent conceptions. As a result, the research concerning the design and implementation of such interventions that prevent learners from reverting back to initial conceptions appears to be of great importance for science education. There are few studies that followed up students for the long-term effects of the interventions, those that hold promise to achieve the change in students’ conceptions of scientific concepts (Georghiades, 2000, 2004; Johnson, 1998c; Kabapinar et al., 2004; Taber & Watts, 2000; Trundle, Atwood, & Christopher, In press; Tytler, 1998a, 1998b; Wu & Tsai, 2005). There is still a need for research to identify how multiple representations contribute to the durability of newly constructed scientific conceptions in many different science topics, one of which is the particulate nature of matter. Purpose of the Study The purpose of the current study was to understand and describe high school introductory chemistry students’ conceptual understandings of the PNM before, immediately after, and three-months after they complete the interventions called ReformBased Teaching with Multiple Representations (RBTw/MR) and Reform-Based Teaching (RBT). Specifically, to gain insight into the characteristics of students’ conceptions of the PNM, this study intended to identify and portray the conceptual pathways (Scott, 1992) that individual students engage in each intervention from the pretest (before the intervention) to the post to the delayed posttest (three-months following the intervention).
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This study also aimed to explore students’ conceptions of each constituent concept of the PNM in the three states of matter from the pretest to the post to the delayed posttest. The ultimate goal of the study was to investigate the effectiveness of the instructions of the RBTw/MR and the RBT in light of qualitative and quantitative evidence as to promoting conceptual change in students’ conceptual understandings of the aspects of the PNM and the durability of scientific understandings constructed during the instruction. Research Questions The following research questions guided the current research study: (1) What are the types of conceptual understandings held by high school students about the aspects of the PNM just before, immediately after, and three-months after completion of the RBTw/MR and the RBT instruction? (2)
How does the conceptual understanding of high school students on the aspects of the PNM change from preinstruction to post and to delayed posttest administered three-months after completion of the RBTw/MR and the RBT instruction?
(3) How do high school students’ types of conceptual understandings of the PNM differ immediately after, and three-months after completion of the RBTw/MR and the RBT instruction? (4)
How do the two groups compare just before, immediately after, and three-months after completion of the RBTw/MR and the RBT instruction?
(5) What are the conceptions held by high school students about each scientific aspect of the PNM just before, immediately after, and three-months after completion of the RBTw/MR and the RBT instruction?
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Significance of the Study This study contributes to the science education research literature in three distinct ways. First, few studies (Bunce & Gabel, 2002; Rohr & Reimann, 1998; Snir et al., 2003; Tasker & Dalton, 2006; Williamson & Abraham, 1995) have used multiple representations as a teaching pedagogy to promote change in students’ understandings of the aspects of the PNM. In addition, almost none of these studies used students own drawings as a multi-representational instructional strategy (Van Meter & Garner, 2005). The current quasi-experimental study attempted to investigate if teaching the aspects of the PNM through multiple representations in the inquiry context with emphasis on oral and written discourse enhances students’ scientific understanding of the PNM. The results of the study provide evidence to make suggestions for how the aspects of the PNM should be taught and for further research on examining the effectiveness of the instructional interventions of the RBTw/MR and the RBT in teaching and learning of the other concepts in chemistry. Second, very few studies longitudinally looked into students’ conceptual understandings (Georghiades, 2000) in different domains of science. Thus far, no study also searched for how multi-representational instruction contributes to the durability of students’ scientific understandings of the PNM. The results of the study have potential to inform science teachers, teacher educators, and science education researchers on the effectiveness of multi-representational teaching in maintaining students newly constructed conceptions of the PNM for an extended period of time. Third, many of the previous studies (Johnston, 1990; Lee et al., 1993; Scott, 1992; Sequeira & Leite, 1990; Singer et al., 2003; Snir et al., 2003; Stavy, 1988, 1989) were 12
conducted with middle school students concerning their conceptions of the PNM, but only a few studies (Griffiths & Preston, 1992; Haidar & Abraham, 1991; Johnson, 1998c; Kabapinar et al., 2004; Pereira & Pestana, 1991) have specifically examined high school students’ conceptions of the PNM so that the results of the present study are of significance to the field of students’ conceptions literature as it extends the knowledge base that currently exists in this field. Definition of Terms Particulate Nature of Matter (PNM): Everything that takes up space is made up of tiny invisible/indivisible particles with nothing between them. Those particles in all three states of matter are in continuous motion. Attractive forces of varying strengths exist between the particles. Multiple Representations: are the ways people communicate ideas or concepts by representing them… externally—taking the form of spoken language (verbal), written symbols (textual), pictures … or a combination of these forms (Tsui & Treagust, 2004). Reform-Based Teaching (RBT): The instruction of the RBT was structured with regard to the teaching pedagogies recommended by the NSES (NRC, 1996). Thus, the RBT placed emphasis on (NRC, 1996, p.52): • student understanding and use of scientific knowledge, ideas, and inquiry processes. • providing opportunities for scientific discussion and debate among students. • continuous monitoring of student understanding through student activity sheets, and journal entries.
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Concept: is “the fundamental building block of knowledge, and define[d] …as perceived regularities or patterns in events or objects” (Novak, 2004, p.23). The concepts of the PNM that were the focus of the current study consisted of 1) all matter is made up of particles, 2) the patterns in arrangement of and spacing between the particles in the three states of matter, 3) all matter is in continuous motion, 4) attraction forces act between the particles of matter, and 5) nothing exists between the particles. Alternative Conception: is conceptual understanding which is at variance with the scientifically accepted norms (Hewson & Hewson, 1983). Type of conceptual understanding: are descriptive labels/categories that indicate the extent to which students conceptually understand the concepts/aspects of the PNM that were focus of the current study. Scientific Understanding of the PNM: include scientific conceptions of all six concepts defined above (see definition of concept) as well as the concepts of the uniform distribution of gas particles in an enclosed space and the change in density of particles when a gas turns into a liquid. Scientific Fragments: include a subset, but not all, of the concepts that identify scientific understanding of the PNM with no alternative conception. Alternative Fragments: include a subset, but not all, of the alternative conceptions identified among the participants of the current study (see Table 3.4 in Chapter 3). Scientific with Alternative Fragments: dominantly include a subset of scientific conceptions of the PNM with at most three fragments of alternative conceptions. No understanding: exhibit no or irrelevant evidence of understanding the aspects of PNM. 14
CHAPTER 2 LITERATURE REVIEW Introduction This chapter provides an overview of the foundational learning theories that this study is drawn from and reviews the literature that is pertinent to the current study. This chapter includes three major sections. First section is devoted to an overview of constructivist and conceptual change views of learning. The second section involves the review of literature on students’ alternative conceptions of the particulate nature of matter (PNM) and the instructional pedagogies that researchers adopted for remediation of students’ particular alternative conceptions of the PNM. The third section includes the overview of multi-representational learning theories and the survey of the literature that investigates the effects of multi-representational instruction on student learning outcomes. The instructions of the RBT and the RBTw/MR, which were under consideration of the current study, particularly attempted to create learning environments that promote change in students’ conceptual understandings of the PNM. As contended by Hewson, Beeth and Thorley (1998), the basis of teaching for conceptual change rests on the premise that “effective teaching needs to be rooted in an understanding of how students learn” (p.199). In that sense, laying out contemporary answers to the question of “how do
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students learn?” gains great importance in accomplishing the objectives of the present research. However, no single answer corresponds to this specific question in the educational literature. Theories developed in an effort to explain how students learn have evolved over time with the changes in psychological and educational ideas (Driver, 1995). Since the 1970s, science educators have become advocates of the constructivist view of learning. Even though each learning theory under the overarching theme of constructivist paradigm offers an alternative perspective to depict the occurrence of student learning, they all interweave, complementing one another (Marin, Benarroch, & Jimenez Gomez, 2000). Thus, the subsequent sections discuss the constructivist views of learning on which this study is based. Constructivism The most important factor influencing the meaningful learning of any new idea is the state of the individual’s existing cognitive structure at the time of learning…if new material is to be learned meaningfully there must exist ideas in cognitive structure to which this material can be related (Ausubel & Robinson, 1969, p.143). An excerpt stated in part above calls special attention to the key feature of the constructivist epistemology in which learners’ existing knowledge is recognized and appreciated given its potential to give rise to the construction of new knowledge (Taber, 2003). Learning science involves both individual and social constructivist views where the focus is on the students, with learning being the outcome of their own interpretation of the natural world in a particular social context (Driver, Asoko, Leach, Mortimer, & Scott, 1994; Duit & Treagust, 1998; Leach & Scott, 2000). In this respect, the following sections discuss the basis of the individual and social constructivist views of learning.
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Individual Constructivism The individual constructivist view of learning originated from Piaget’s (1970) work. He highlighted the active role of the learner in the construction of knowledge, stating that “intelligence organizes the world by organizing itself” (Piaget, 1937, p.311). According to Piaget, learners actively assimilate or accommodate new knowledge to fit it into their existing cognitive structures. The processes of knowledge construction that students experience and the nature of the meaning that they derive from the new learning situations deeply rely on the knowledge that already exists in their cognitive structures (Leach & Scott, 2003). Therefore, the knowledge that students bring to science classrooms require particular interest by teachers in order to foster student learning and offer them opportunities to develop school science views of natural phenomena (Driver, 1995; Tytler, 2002). Although the research on students’ conceptions demonstrates dissimilarities with the Piagetian view of learning as to its concentration on domain specific knowledge, it, indeed, adopts the pedagogical implications of the Piagetian view. As Driver et al. (1994) stated that Both view meaning as being made by individuals, and assert that meaning depends on individual’s current knowledge schemes. Learning comes about when those schemes change through the resolution of disequilibration. Such resolution requires internal mental activity and results in a previous knowledge scheme being modified. Learning is thus seen as involving a process of conceptual change” (p.6). A variety of perspectives of conceptual change that stemmed from the individual constructivist view of learning are discussed in detail later in this chapter. Nowadays, the exclusive interest in individual’s nature of understandings has shifted to the role of
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teachers or peers and the social context in learning (Jones & Brader-Araje, 2002; Tytler, 2002). The next section focuses on the discussion concerning the key aspects of the social constructivist view of learning as well as its pervasive role in teaching and learning of science. Social Constructivism The social constructivist view of learning was basically rooted in Vygotsky’s work (Vygotsky, 1978), which asserted that the language as a mediator of thought plays a central role in the development of learners’ higher cognitive functions such as scientific concepts (Howe, 1996). Consistent with the Vygotskian view, learners are able to construct scientific understandings of the domain through the processes of internalization in which science concepts are first negotiated between students before being incorporated into the learners’ cognitive structures (Scott, 1996). In the process of constructing scientific knowledge, negotiation with peers creates; 1) a forum in which previously existing implicit ideas can become explicit; 2) a situation in which individuals have to elucidate their own understandings; 3) an opportunity for individuals to build on each other’s ideas to arrive at a scientifically accepted explanation (Driver, 1995). The contemporary vision of science teaching purposed in the National Science Education Standards also placed substantial emphasis on science as argument and explanation (National Research Council [NRC], 1996, p.113). That is, in science education reform, the priority was granted for the development of a language for talking about science and scientific ideas, focusing on making students’ ideas explicit to the teacher and their peers (NRC, 2000). Along the same line, recognizing the critical role of language in science learning, Yore and Treagust (2006) claimed that “no effective 18
science education programme would be complete if it did not support students in acquiring the facility of oral science language and the ability to access, produce, and comprehend the full range of science text and representations” (p.296). Oral and written discourses as communication tools for doing science serve the dissemination of the findings drawn from the scientific inquiry. In fact, these two mediators of scientific knowledge do not stand alone; that is, removal of one of these communication means impairs the act of science (Norris & Phillips, 2003). Oral and written language and semiotic tools of science such as tables, illustrative graphs and pictorial models (Lemke, 1998) offer a common ground for social interaction and multiple modes of thinking (Yore & Treagust, 2006). Both oral and pictorial modes of language not only facilitate the meaning-making between learners but also manipulate individual’s cognitive functioning by stimulating and organizing their thought processes (Hodson & Hodson, 1998; Scott, 1996). Using the semiotic tools of science, students hypothesize, question, observe and evaluate the natural phenomena as well as negotiate their reasoning and experiences to others (Mason, 1998; Mason & Boscolo, 2000). In contrast to the Piagetian view where individuals’ cognitive development is considered to be a prerequisite of learning, Vygotsky (1978) argued that Learning awakens a variety of internal developmental processes that are able to operate only when the child is interacting with people in his environment and in cooperation with his peers. … Learning is not development; however, properly organized learning [italics added] results in mental development and sets in motion a variety of developmental processes that would be impossible apart from learning (p.90).
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Accordingly, Vygotsky introduced the notion of zone of proximal development (ZPD) to draw attention to the issue with learning that needs to be compatible with the learners’ level of development (Palincsar, 1998). For Vygotsky, ZPD is “the distance between the [learners’] actual development level … and the level of potential development as determined through problem solving under adult guidance or in collaboration with more capable peers” (p.86). He acknowledged creating learning tasks that move ahead of learners’ development level to be critical for good learning (Howe, 1996). In that sense, a key pedagogical aspect of the Vygotskian view of learning, scaffolding, aims at advancing students’ learning through social interactions at the same time as nurturing their cognitive development (Hodson & Hodson, 1998). In summary, the constructivist views in education overrode every aspect of the current study, particularly research methodology and teaching pedagogies that were incorporated into the interventions of the RBT and the RBTw/MR. Research methodology was guided by the constructivist view in regards of employing a range of methods of data collection and analysis. Moreover, the interventions of the RBT and the RBTw/MR particularly facilitated student interaction with the natural phenomena and also their peers as students predicted, observed, and expressed their ideas in relation to the submicroscopic occurrences of various natural phenomena. The next section provides the overview of the theoretical basis of the conceptual change learning. Conceptual Change Learning Conceptual change is a research paradigm that was derived from the field of students’ alternative conceptions and the individual constructivist view of learning.
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Conceptual change is “an outgrowth of constructivist epistemology in which knowledge acquisition is viewed as a constructive process that involves actively generating and testing alternative propositions” (Tyson, Venville, Harrison, & Treagust, 1997, p.387). Conceptual change learning has been grounded in two independent fields of research: science education (Mortimer, 1995; Posner, Strike, Hewson, & Gertzog, 1982) and cognitive-developmental psychology (Chi, Slotta, & Leeuw, 1994; Vosniadou, 1994). The following sections include the discussion on the plural views of conceptual change learning rooted in these two research traditions.
The Conceptual Change Learning in Science Education This section begins with the articulation of the earliest Conceptual Change Model (CCM) proposed by a group of science educators following with the arguments in science education community regarding the nature of conceptual changes that take place in students’ conceptual frameworks. This section, then, continues with the overview of conceptual profile change view. The highly recognized Conceptual Change Model (CCM) in science education was developed by Posner et al. (1982), and then, was elaborated and revised in additional studies (Hewson, 1981, 1985; Hewson & Thorley, 1989; Strike & Posner, 1985, 1992). This model is primarily based on an analogy between Piaget’s notions of assimilation and accommodation in learning but uses the terms that refer to theory change in science, namely, normal science and scientific revolutions (Kuhn, 1996). Posner et al. (1982) conceived conceptual change learning as a rational process and attempted to portray how “people’s central, organizing concepts change from one set of concepts to another set,
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incompatible with the first” (p.211). According to Posner et al., conceptual change occurs in manners of either assimilation “where students use existing concepts to deal with new phenomena”, or accommodation that involves the process of “replacing and reorganizing the learners’ central conceptions” (p.212). In the articles of Posner et al. (1982) and Strike and Posner (1992), the only strong restructuring in learners’ preconceptions, as they called accommodation, was viewed as conceptual change. However, Hewson (1981) and Hewson and Hewson (1992) drew attention to the issue of disregarding weak restructuring as conceptual change and argued for valuing weaker changes in learners’ existing conceptions within the context of the CCM. In this respect, Hewson (1981) suggested the notions of conceptual capture and conceptual exchange, which respectively imply weak and strong changes in learners’ existing conceptions. Hewson claimed that the new concept could either be rejected or incorporated into the learners existing conceptions in three ways. The new concept can a) be memorized by rote, b) be captured by the prior knowledge, that is the process in which individuals possess the old idea and the new one together without recognizing any inconsistency between them, or c) replace the old one, but be reconciled with the existing knowledge framework. Similarly, Dagher (1994) also pointed out the importance of the weak changes in learners’ conceptions and suggested that “restricting worthwhile conceptual change to the radical type is equivalent to restricting worthwhile science to revolutionary science” (p.609). The components of the conceptual change include status of conceptions and conceptual ecology. The status is “an indication of the degree to which he or she knows and accepts” an idea held by him/herself (Hewson et al., 1998, p.200). “A central 22
prediction of the conceptual change model is that conceptual changes do not occur without concomitant changes in the relative status of changing conceptions” (Hewson & Hewson, 1992, p.60). There are four conditions that must be fulfilled to change conceptions that are at odds with scientific views. Learners must be dissatisfied with the existing conception. This is the precondition for activating the conceptual change learning. There has to be a remarkable reason that makes learners believe that what they previously consider as an idea, a belief, or a truth no longer works. The new conception must be intelligible, that is, individuals basically understand what it means and express the idea in their own words. However, they may not necessarily believe that idea as a possibility. The new conception also must be initially plausible, which involves that the new conception that learners are faced with seems to be entirely reasonable, but conflicts with their prior knowledge. Then, learners would be able to exchange or reorganize their current conception with a scientifically acceptable one. The new conception must be fruitful. The conception, which is intelligible and plausible, may possess additional status and turn out to be fruitful. The fruitful conception provides additional potential to learners and enables them to make use of that particular concept in various contexts. The fruitful concept “suggests ways of approaching the world and opens new avenues of inquiry” (Strike & Posner, 1992, p.149). In a broad sense, the three conditions, namely intelligibility, plausibility, and fruitfulness, offer a relatively linear trend as to the status of a conception. Thus, a conception can be intelligible, intelligible and plausible, or intelligible, plausible and fruitful, but without satisfying the preceding condition, a conception’s status can never advance to a higher level (Hewson, 1981).
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The conceptual ecology “provides the context in which the conceptual change occurs and has meaning” (Hewson & Thorley, 1989, p.541). Therefore, conceptual ecology appears to be an ecological niche where conceptions survive, gain significance, and make more sense to the learner. An array of factors such as religious or cultural beliefs or critical events experienced by the learners may influence the robustness of the naïve conceptions that they hold. If these naïve (alternative) conceptions are deeply embedded in learners’ knowledge frameworks, the learners may refuse to change their naïve conceptions in favor of scientific conceptions. The components of the conceptual ecology are identified by Strike and Posner (1985) as: a) anomalies, b) analogies and metaphors, c) exemplars and images, d) past experience, e) epistemological commitments, f) metaphysical beliefs and concepts, and g) other knowledge. Hewson (1985) pointed to the significance of the epistemological commitments as part of the conceptual ecology in identification of the degree to which learners hold onto their current conceptions. Epistemological commitments are characterized as a judgment of the knowledge for individuals to make decisions to believe in a new concept or not. He also specified the features of the epistemological commitments as: a) internal consistency, which gives rise to the construction of knowledge that takes place as a consequence of bringing the pieces together in which each piece is plausible to individuals in different knowledge categories, and b) generalizability, which refers to the acceptance of a conception as a truth in which it is applicable in a diverse range of knowledge frameworks.
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A decade after the article regarding the theory of conceptual change learning was published by Posner et al. (1982), Strike and Posner (1992) revised the original CCM in the light of critiques directed to the CCM by educational psychologists. For instance, Pintrich, Marx, and Boyle (1993), in their review of the CCM, brought up the issue of emphasis situated on the cognitive aspect of the conceptual change learning. Then, they took a position by advocating a hot model of conceptual change learning that is influenced by personal, motivational, and social factors. In this context, they used the metaphor of cold to depict the learning process that is solely promoted by logic and scientific findings. They maintained that “cognition-only models of student learning do not adequately explain why students who seem to have requisite prior conceptual knowledge do not activate this knowledge for many school tasks” (p.167). Considering all these criticisms, Strike and Posner (1992) suggested that: A wider range of factors needs to be taken into account in attempting to describe a learner’s conceptual ecology. Motives and goals and the institutional and social sources of them need to be considered. The idea of a conceptual ecology thus needs to be larger than the epistemological factors suggested by the history and philosophy of science (p.162). Thus, the CCM turned out to be a dynamic and multidimensional learning perspective with the integration of diverse ingredients of learning. Driver et al. (1994) claimed that a model of learning that involves the replacement of existing conceptions with the new ones ignores the possibility of learners having multiple conceptions, each of which may fit in a specific context. Empirical studies also support the idea of the coexistence of multiple conceptions within learners’ knowledge framework as being “stable and coherent explanatory schemes” (Taber, 2000, p.399). For example, in the case study reported by Scott (1992), the student participant was 25
interviewed about her conceptions of the PNM. Even though she developed a scientific view of the submicroscopic properties of matter, she made a clear distinction between her scientific and everyday explanations and rejected to use particle ideas in her daily life. Drawing upon the line of research that argued for likelihood of the coexistence of multiple conceptions in learners’ knowledge framework, Mortimer (1995) proposed the notion of a conceptual profile. This notion was drawn from the idea of using multiple ways of thinking in different domains without necessarily replacing the previous concepts with the new ones. The conceptual profile change, then, is viewed to be an evolutionary learning model rather than revolutionary as suggested by Posner et al. (1982). The conceptual profile change assumes that “the process of construction of meaning does not always happen through an accommodation of previous conceptual frameworks in the face of new events or objects, but may sometimes happen independently of previous conceptions” (Mortimer, 1995, p.268). In the context of evolution of particle ideas, Mortimer (1995) distinguished the categories that constitute the different zones of conceptual profiles of the atom. The first zone of atomic profile is a realistic one in which learners view matter as continuous. The second zone of the profile is called substantialism at which students conceive of atoms as grains of matter that display macroscopic properties without having a conception of vacuum between them. The third zone signifies the classic notion of the atom as the basic unit of matter so that it is conserved in chemical reactions and its behavior is controlled by mechanical laws. The fourth zone of the atomic profile comes out as a product of quantum mechanics. In this case, the atom as a quantum object is not considered to be a material particle but is explicated by mathematical equations, (e.g., Schrodinger 26
equation). Mortimer also asserted that teaching for conceptual profile change does not necessarily create a conceptual change, but enhances students’ conceptual profile zone by increasing their consciousness of theory change. Accordingly, students would be able to differentiate the hierarchical framework of each idea in different scientific domains. In summary, Posner et al. (1982) put forward the learning model that conceptual change occurs in the case of replacement of students’ alternative conceptions with the scientific views. Yet, a model of conceptual profile change by Mortimer (1995) differed from the CCM in terms of accepting the view that learners’ ideas progress, but naïve conceptions that they hold continue to be present in their knowledge frameworks. Hence, any degree of conceptual change takes place in students’ conceptual frameworks is regarded to be conceptual progress/change as opposed to the view that seeks only radical restructuring in students’ conceptual frameworks for conceptual change. The next section focuses on the discussion of the conceptual change perspectives held by cognitive developmental psychologists.
The Conceptual Change Learning in Cognitive-Developmental Psychology Cognitive developmental research has been largely influenced by Piaget’s constructivism, which suggests that knowledge is a human construction and built through learners’ interactions with the natural environment. Therefore, it is no surprise to observe that students come to science classes by having well-established knowledge framework about the physical world based on their everyday experiences. Vosniadou (1994) has called these conceptions as entrenched presuppositions that are embedded within coherent explanatory framework theories. These framework theories reflect learners’
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basic epistemological and ontological commitments and refer to a cognitive system that individuals create to interpret their observations of the natural world, including the information provided by their culture (Vosniadou, 1994, 2002). A framework theory is an explanatory system with some coherence, but frequently diverges from a scientific theory in terms of lacking the systematicity, abstractness and its social/institutional nature (Vosniadou, 2002). Learners also build specific theories based on their own observations of the world and the knowledge they receive from the culture. These specific theories are constrained by the entrenched presuppositions that exist in learners’ explanatory framework. These specific theories “consist of a set of interrelated propositions or beliefs that describe the properties and behavior of physical objects” (Vosniadou, 1994, p.47). These two constructs, namely the framework theories and specific theories, contribute to the learners’ representation of the physical world, which is called mental models. Vosniadou defined mental models as “dynamic and generative representations, which can be manipulated mentally to provide causal explanations of physical phenomena and make predictions about the state of affairs in the physical world” (Vosniadou, 1994, p.48). Mental models generated by individuals during cognitive processing assist the incorporation of new information into existing knowledge frameworks. According to Vosniadou, conceptual change is a gradual process and requires constant enrichment and revision in knowledge structures. Enrichment is the simple form of conceptual change that occurs in a way that new information is added to the previous conceptual framework through the means of accretion. Revision, however, involves restructuring within a framework theory when individuals perceive the conflict between their existing knowledge base and the knowledge constructed through interaction with nature. 28
However, Chi and her colleagues (2002; 1994) brought a different view to the interpretation of conceptual change. According to Chi et al. (1994) the difficulty of learning certain science concepts is deeply associated with “the existence of a mismatch or incompatibility between the categorical representation that students bring to an instructional context, and the ontological category to which the science concept truly belongs”(p.34). Chi and Roscoe (2002) put forward that conceptual change occurs when the miscategorized conceptions (misconceptions) are repaired by the reassignment of those of the conceptions to the scientifically accepted categories. A framework of conceptual change model proposed by Chi et al. revolved around the three assumptions (Chi & Roscoe, 2002; Chi et al., 1994). An epistemological assumption supposes that entities in the world belong to three major ontological categories: Matter (things), Processes, and Mental States. There are also hierarchical subcategories embedded in each of these categories. Subcategories in a given major category are ontologically distinct from any subcategory that belongs to other major category. In this framework, Chi et al. (1994) defined conceptual change as the reassignment of a concept to an ontologically distinct category across major categories such as from Matter to Processes. A metaphysical assumption concerning the nature of scientific concepts refers to Constraint-based Interaction. Chi et al. (1994) argued that many science concepts fall into this category (e.g., electricity, heat, light and so on). The concept of electric current, for example, does not fit into a category of either Matter or properties of Matter, but was classified as a Process, because the creation of electric current depends on the existence of moving charged particles and of the electric field. 29
A psychological assumption regarding the nature of alternative conceptions claims that the placement of concepts into ontologically inappropriate categories generates alternative conceptions. Because students are usually not conscious of their alternative conceptions, the achievement of conceptual change becomes challenging.
Summary Although researchers in the fields of science education and cognitivedevelopmental psychology have distinctive approaches to the conceptual change learning, both lines of researchers consider students’ preexisting conceptions as a main target to start with and explain the processes of knowledge construction. However, a majority of studies provided a range of evidence that students’ preexisting conceptions are robust in nature and frequently resistant to change (Duit, 2006; Stepans, Beiswenger, & Dyche, 1986). Duit and Treagust (1998) argued that the conceptual change observed in students’ understanding of science concepts often times appears to be limited. In addition, many of the findings pertaining to research on conceptual change learning showed that the prior conceptions could never be entirely extinguished and then replaced by the scientific ideas; in fact, the previous ideas continue to be maintained in particular contexts (Duit & Treagust, 2003; White, 1989). Therefore, Mortimer’s (1995) Conceptual Profile Change seems to be a reasonable alternative to all other perspectives due to the fact that conceptual profile change does not necessarily require the substitution of alternative conceptions with the scientific views. Therefore, students’ plural conceptual understandings can be sustained in their conceptual frameworks and be fruitful for them in different contexts. Yet, improving students’ metacognitive skills becomes an important
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aspect of conceptual change pedagogy, because once students gain control over their own conceptions, they should be able to intentionally manipulate their plural conceptions and utilize them in the appropriate contexts. The current study did not specifically look into students’ metacognitive processes or explicitly teach metacognitive strategies to the students during the RBT and RBTw/MR instruction. As the construct of metacognition is acknowledged to be a significant component for achieving the change in students’ alternative conceptions, journal prompts and the questions included in the activity sheets implicitly intended to motivate student metacognitive thinking. The following section introduces the construct of metacognition and discusses how metacognition contributes to conceptual change. Metacognition and Intentional Conceptual Change The multifaceted concept of metacognition involves “the knowledge, awareness and the control of one’s own knowledge” (Baird, 1990, p.184). Similarly, Hennessey (2003) described metacognition as individuals “inner awareness” about their processes of learning, what they know (content knowledge) and their contemporary cognitive state. Gunstone (1994) has offered several assertions to articulate the features of metacognition, all of which are complementing one another: • • • •
The components of metacognition (knowledge, awareness and control) can be learned as a consequence of experience. Students can develop metacognitive abilities when they are provided appropriate learning opportunities. Metacognitive abilities largely affect the extent of students’ achievement of normal learning goals. Metacognitive learners are able to monitor, integrate and extend their own learning.
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According to Gunstone, students need to be metacognitive in their processes of learning in order to attain conceptual change. Some of the metacognitive activities that are inherent to conceptual change consist of “commenting on and contrasting these explanations, considering arguments to support or contradict one or other explanation, and choosing one of these possible explanations” (Hewson et al., 1998, p.205). These classroom interactions are considered to be the only ways in which students demonstrate evidence of the status of ideas that they learned, allowing the monitoring of the learning by the teacher (Beeth, 1998; Hewson et al., 1998). Bereiter and Scardamalia (1989) defined intentional learning as “cognitive processes that have learning as a goal rather than an incidental outcome” (p.363). Based on this definition, it seems that intentional learning comprises both cognitive and metacognitive elements of learning. In a specific sense, a fundamental basis of intentional learning consisted of the notions of cognitive goals, conscious control, regulation of learning in a metacognitive manner and purposive use of knowledge (Bereiter & Scardamalia, 1989; Sinatra & Pintrich, 2003; Vosniadou, 2003). Hennessey (2003) claimed that metacognitive processes at the evaluative level give rise to intentional conceptual change such that control of cognition encourages students’ ability to monitor and finely adjust their thinking as they accomplish goal-directed tasks. Moreover, the critiquing of cognition engages students in the kinds of thought processes in which they purposefully evaluate their unrelated pieces of conceptions to bring them together in a meaningful manner (Hennessey, 2003). Vosniadou (2003) also discussed possible ways that assist the occurrence of intentional conceptual change. Vosniadou put forward that individuals’ ability to hold and simultaneously manage multiple representations of the 32
phenomenon induces intentional conceptual change, due to the fact that those individuals are likely to be able to monitor and be metaconceptually conscious of their own manifold conceptions. Two pieces of evidence that indicate a lack of intentional learning are identified as internal inconsistencies and lack of explanatory coherence (Vosniadou, 2003). Internal inconsistency has to do with students’ inconsistent use of the scientific concept in different instances. In other words, while students apply the scientific concept properly in one occasion, they sometimes fail to use that specific concept in a proper manner in another occasion. Vosniadou argued that as students are introduced to scientific knowledge, the structure of their initial explanatory framework loses its stability and starts being reorganized by incoherent context dependent explanations. Because the coherent explanatory framework is considered to have a potential to explain a range of phenomena, tying/or restricting newly constructed knowledge to a specific task/or limited contexts is delineated with the term “inert knowledge” (Vosniadou, 2003, p.395). Thus far, this chapter laid out learning perspectives by which this study was motivated. The following section consists of the review of literature that articulates the students’ typical alternative conceptions of the PNM. Students’ Alternative Conceptions of the Particulate Nature of Matter Students develop intuitive ideas about the natural occurrences with regard to their everyday interactions with the physical environment. Over the last three decades, a large body of research has been accumulated in efforts to identify and characterize students’ everyday conceptions with various age groups and in a wide range of topics, including
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the particulate nature of matter (Duit, 2006). Researchers have referred to those students’ non-scientific conceptions as preconceptions (Ausubel, 1968), misconception, alternative frameworks (Driver & Easley, 1978), children's science (Osborne, Bell, & Gilbert, 1983), knowledge in pieces (diSessa, 1993) and synthetic mental model(s) for instruction generated alternative conceptions (Vosniadou, 1994). Of the literature on students’ conceptions, research that explored students’ conceptions of the particulate nature of matter (PNM) sets the background for the current study. The kinetic-molecular theory contains certain premises about both matter and the behavior of particles of which it is made. These premises include the following aspects about the nature of particles in the solid, liquid and gas state (Holtzclaw, Robinson, & Odom, 1991). 1. Solids, liquids and gases are composed of invisible particles with a vacuum between the particles. 2. Gas particles are in continuous, completely random motion, and collisions between gas particles are perfectly elastic. 3. Particles of liquids move randomly, but much more slowly than in gas state. 4. Although most particles of solids do not move about, they do vibrate. 5. At relatively low pressures, the average distance between gas particles is substantially large, whereas the particles of solids and liquids are relatively closely packed with similar sized space between the particles. 6. The attraction forces between gas particles can be ignored because of widely spaced particles, but the attraction forces between the particles of solids and liquids are much stronger compared to gas particles. 7. Gas particles are evenly spread out in an enclosed space. Comprehension of almost every topic in chemistry to a great extent hinges on having thorough understanding about the aspects of the PNM. This is because the aspects of the PNM as stated above provide a basis for explaining the nature of atomic structure, bonding, solubility, chemical reactions etc. (Gabel, 1993; Haidar & Abraham, 1991; Harrison & Treagust, 2002). The results of research on students’ conceptions of the PNM 34
indicated that students’ do develop a number of various alternative conceptions about the aspects of the PNM. The subsequent sections discuss the characteristics of those alternative conceptions.
Matter is Continuous Research frequently demonstrated that students perceive matter as being smooth and continuous rather than being made up of discrete, dynamic invisible/indivisible particles such as atoms, molecules and ions. Due to the common sense belief in continuity of matter among students, when students are probed as to whether they are aware of the discrete nature of matter, they usually refuse the idea of matter as being made up of particles (Albanese & Vincentini, 1997). For example, in an interview with the 9th graders, students were asked to draw some water using the particle model. Students either said that it is impossible to perform the task because particles “are so small that no one can see them” (Sequeira & Leite, 1990, p.224) or they ended up with a continuous picture of the water. Benson, Wittrock, and Baur (1993) examined a total of 1098 representations of air in a closed flask drawn by students from second grade to university level. The results revealed that nearly 37% of all students considered air as a continuous substance, and the percentage of drawings that provided evidence of the particle model changed from 8% for students in grades 2-4 to 85% for university students. A more recent study by Nakhleh and Samarapungavan (1999) investigated elementary school students’ understanding of the PNM without any specific instruction. Students were interviewed using substances familiar to them such as a cube of sugar, a
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wooden toothpick, liquid water, and a piece of copper wire. Twenty percent of students held a continuous view of matter, stating that the item was “made of one piece” or “not broken down”. Nakhleh and Samarapungavan (1999) inferred that “solid matter with no apparent granularity or softness seems to be more difficult for children to conceptualize as being composed of particulate or molecular matter” (p.794). In addition, Nakhleh and Samarapungavan (1999) asserted that for students, it is often times counterintuitive to conceive of hard solids, (e.g., wood and copper) as being made of particles in constant motion. In general, the researchers put forward that students do not form particle ideas consistently across all substances. They form local ideas about matter, and they believe that some forms of matter are particulate and others are not (Nakhleh & Samarapungavan, 1999; Nakhleh et al., 2005; Pozo & Gómez-Crespo, 2005; Stavy, 1988, 1990). For example, 13 of the 15 primary school students identified wood as continuous, but 10 of the15 participants recognized the helium-filled balloon as containing particles (Nakhleh & Samarapungavan, 1999). Similarly, whereas 6 of the 9 middle school students’ exhibited a macroscopic view of matter for the sugar cube, toothpick, and copper wire, they held a submicroscopic view of matter for such substances as water and helium (Nakhleh et al., 2005). Moreover, the study by Stavy (1988) showed that students (8th grade) apply the particle ideas to explain the term gas, but do not transfer their understanding of the PNM to explain the terms solid and liquid.
Attributing Macroscopic Properties of Matter to its Particles Research has consistently reported that students tend to attribute observable properties of matter such as color, hardness, hotness/coldness, smell, shape, and physical
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state to its submicroscopic particles, (e.g., atoms and molecules). Technically, the macroscopic properties of the matter/substance are considered to be collective properties of the particles and cannot be attributed to a single particle. However, students envision atoms as the smallest part of a macroscopic object, which retain the macroscopic characteristics of an object (Albanese & Vincentini, 1997). Perhaps students conceive of atoms to be the final link in a process of subdivision, instead of the building blocks of the matter that collectively explain the emergent properties of the matter (Pfundt, 1981). Griffiths and Preston (1992) asked 12th grade students to sketch what they would see if they could look at a molecule of water under a microscope. Some of these students thought that a water molecule is spherical with particles spread throughout, and some others believed that water molecules have different shapes depending on what phase they are in. The findings of another study revealed that 80% of students attributed a macroscopically observed color of various substances to their single particles (Albanese & Vincentini, 1997). Ben-Zvi, Eylon and Silberstein (1986) developed a questionnaire to examine the 10th grade students’ beliefs about matter. Students compared the properties of a piece of copper wire and a single atom isolated from the gas that formed when the copper wire vaporized. About 50% of the students said that the properties held by a copper wire such as electrical conductance, color, and malleability also apply to the properties of a single atom. The other examples of attribution of macroscopic properties on to submicroscopic particles are that water is hot/cold, so its molecules are hot/cold; naphthalene smells, so do naphthalene molecules; alcohol is liquid so its molecules cannot be hard and they must be tiny droplets (Andersson, 1990; Lee et al., 1993).
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Matter is Mostly Static Students often perceive particles of matter as static, particularly in the solid state, however, particles in all three states of matter are in continuous motion/or vibration, For example, Scott (1992) asked a student to draw the picture of the air in the closed flask after some of the air has been taken out by using a pump. In response, she stated, “everything will have been pumped sort of upwards” (Scott, 1992, p.206) and drew the picture shown in Figure 2.1. Moreover, Lee et al. (1993) stated that as opposed to the scientific conception of the properties of gases, students believed that air flows like water from one place to another, and it is unevenly spread out. Regarding the situation of compression of air in a syringe, students thought that air molecules were pushed forward, moving toward the opening of the syringe. A student stated that “because the air is all bunched up together. The plunger is pushing the air forward” (Lee et al, 1993, p.261). A frequently cited study by Nussbaum and Novick (1981) demonstrated that a constant increase in percentages of students who explain uniform distribution of gas particles using the notion of intrinsic motion of particles was observed over grade levels of elementary through university. However, even at the university level, the percentage of students who held a scientific understanding of this particular concept never reached the level of 50%. Additionally, about 30% of the elementary and middle school students and 10% of the high school and university students represented a static particle picture in their drawings. Johnson (1998c) mentioned that students easily utilize the idea of the intrinsic motion of particles in the gas state, but when they were probed to explain why sugar dissolves when left in water without stirring, almost none of the students were able to relate this process to the ideas of intrinsic motion of the water particles. An interview 38
excerpt from the Johnson’s study adequately exemplifies the way in which students think about the motion of particles in three states of matter: “the sugar particles would be staying still, the water particle moving around a bit and the gas particle flying off” (p.406).
Figure 2.1: The closed flask after some of the gas was taken out (Scott, 1992, p.208).
Existence of some Materials between Particles Students mostly believe in the presence of air or some other substance between the particles of matter, whereas particles exist within an absolute empty space. It seems that the well-known principle accepted by most scholars in the middle ages “nature abhors a vacuum” (Nussbaum, 1998) still pertains to students’ way of thinking. However, it is essential to note that developing the concept of a vacuum between the particles took hundreds of years for scientists. Thus, for students, developing the notion of matter as discrete particles with an absolute vacuum between them may demand time and proper experiences as well. For example, Ebenezer and Erickson (1996) asked students a question as to how sugar dissolves in water. A student held the idea that there are small pockets of air among water molecules, and sugar molecules drives these out and occupy
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the empty spaces. The excerpt from the interview as follows: “it [sugar] reacts with water and joins in it. Going to the molecules of air that are empty …. Because there is air in the water and sugar takes this place” (Ebenezer & Erickson, 1996, p. 190). Johnson (1998a) questioned students from 7 through 9 grade concerning the case of what happens to the bubbles in boiling water. Many students thought that the bubbles in boiling water were air. A student explained this phenomenon as: “well the heat gives the particles more energy and they can break away from the attraction…. and turn into gas,” considering that the bubbles are air between the water molecules. Additionally, the student said, “as the particles break apart the air is able to come out” (Johnson, 1998a, p.579). The other studies (Johnston, 1990; Lee et al., 1993; Scott, 1992; Sequeira & Leite, 1990) also reported that students strongly held onto the concept of the presence of some substance such as air between molecules and believed that “molecules are in substances, rather than that substances are composed of molecules” or “well, there’s space, but there’s got to be something in it. I mean you do not see open spaces in water” (Lee et al., 1993, p.257). Novick and Nussbaum (1981) asked students the following question, “What is there between the particles as drawn in the evacuated flask?” Twenty percent of elementary and middle school students and 37% of high school and university students did not recognize the concept of empty space between the particles. However, this conception may originate from textbook diagrams that misrepresent the concept of empty space between the particles. Both Andersson (1990) and Harrison and Treagust (2002) found out that textbooks commonly contain such diagrams as seen in Figure 2.2. Such representations give an impression that molecules are floating in some other material. 40
Figure 2.2: Molecules in a liquid: A textbook illustration (Andersson, 1990).
Alternative Understandings Concerning the Relative Spacing of Particles Scientifically, solid particles are in a rigid pattern and closely packed while particles of gases are randomly arranged and substantially spaced out. And also, liquid particles slide past each other with random arrangement, but they are similarly spaced out as particles of solids. However, students usually believe that the relative distances between particles of liquids are intermediate when compared to the distances between particles of solids and liquids (Johnson, 1998c; Johnston, 1990; Lee et al., 1993; Pereira & Pestana, 1991; Scott, 1992; Stavy, 1988). An excerpt from a student interview states that …particles in solid are so close together, it cannot be compressed, ….The particles in a liquid are a little further apart. This means the particles have a little more room to be compressed into. The particles in a gas can be compressed because there is a lot more space between the particles (Johnston, 1990, p.256). This student’s perception of the relative distances between the particles in the three states of matter is in contrast to the scientific view of the spacing between solid-solid, liquidliquid and gas-gas particles at which the ratio between the particles is assumed to be 1:1:10 for solids, liquids and gases respectively (deVos & Verdonk, 1996).
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Alternative Understandings Concerning the Existing Forces between Particles The notion of the existence of attraction forces appears to be the most demanding aspect of the PNM to be comprehended by students. The findings of the two studies (Johnson, 1998c; Johnston, 1990) indicated that very few students distinguish the concept of attraction forces that act between the particles of matter. For example, Johnson (1998c) provided students three different substances (sugar, water, methane) at room temperature and asked the students why these three substances exist in different physical states. Only 14 of the 36 students used the ideas of inherent attraction forces to account for different physical states at room temperature (Johnson, 1998c). The findings of the other studies (Johnson, 1998b; Sequeira & Leite, 1990) revealed that because of students’ lack of knowledge about the presence of the attraction forces between the particles of matter, they usually prefer to use the terms like “separation” and “break apart” to explain the phenomenon of evaporation at the submicroscopic level, instead of connecting this phenomenon to the concept of attraction forces. An interview excerpt from Sequeira and Leite’s (1990) study provided evidence for students’ naïve conception of the occurrence of evaporation: … the heat makes the particles separate more and more from each other and, ….the particles separate more and more, and they will feel the need to look for more space and make them to change from the liquid to the gaseous state and when they reach the gaseous state they seem to get satisfaction with that space (Sequeira & Leite, 1990, p.229).
Particles Expand and Contract Rather than Intermolecular Distances Change From a scientific point of view, substances (except water) expand when heated and contract when cooled. This phenomenon has to do with the change in intermolecular
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distances, but has nothing to do with the change in volume or size of atoms and molecules. However, Griffiths and Preston (1992) found that 40% of students held onto the conception that water molecules in solid state (ice) are the largest, whereas some others believed that water molecules in the solid phase or in the gaseous phase are the smallest. Many students who participated in Lee et al.’s (1993) study confused observable properties of matter with properties of particles and attributed macroscopic changes to the changes in the particles themselves. One student stated; “it [metal ball] wouldn’t go through the ring, because the molecules expanded and caused it to get bigger” (p.263). Summary The results of the research on students’ alternative conceptions of the aspects of the PNM generated a rich knowledge base about students’ conceptual understandings of the particular content as well as enlightened the nature and the scope of the problem with learning the aspects of the PNM. Researchers have developed various pedagogies to promote the scientific views of the PNM among students. The following section presents these instructional pedagogies reported as effective in the past literature. Instructional Approaches to Address Students’ Alternative Conceptions of the PNM According to Millar (1990), a main reason for why students find the aspects of the PNM complicated depends primarily on the way in which this topic is typically taught. Hence, he claimed that students’ reluctance to employ the particle ideas in explaining macroscopic phenomena can be viewed as a “perfectly proper response to a piece of inert knowledge” (p.283). Millar suggested that students’ alternative conceptions of the PNM
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should not be taken for granted as a barrier, but be seen as required steps toward the understanding of the scientific views of the PNM. Therefore, Millar stated that “large and abstract ideas must be taught obliquely, through the accumulation of examples and specific instances, rather than by teaching [italics added] the idea directly and expecting that the learner can assimilate it whole [italics added]” (p.284). Similarly, Harrison and Tregust (2002) suggested that “teaching of particle nature of matter should dispense with the ‘quick tell’ and encourage students to examine the broad range of data pertaining to particles and negotiate communal understanding that are compatible with science and the students’ intellectual level” (p.203). Considering the challenges that students experience in understanding the aspects of the PNM, researchers have designed a series of activities by incorporating various instructional approaches to help students develop scientific understandings of the PNM. Some studies provided the specific examples of the activities that they adopted for teaching the PNM (Johnston, 1990; Meheut & Chomat, 1990; Nussbaum & Novick, 1982; Scott, 1992; Singer et al., 2003; Tsai, 1999). For example, Meheut and Chomat (1990) worked with 8th grade students to examine the effectiveness of the sequence of written and experimental activities that they planned to assist students’ learning of varied aspects of the PNM. Those activities mostly involved the gaseous state, because Meheut and Chomat’s explicitly supposed that the gaseous state offers the best examples for the recognition of empty space and particle motion. Students were introduced to the events of compression of and diffusion of gases (see Figure 2.3) Students interacted with the air filled syringes and then they were asked to write down their individual understanding of what happened at the particulate level and the reason for why it happened when a gas was 44
compressed. The task of compression of gases consisted of concepts of change in volume, pressure and distance between gas particles as well as conservation of mass and motion of particles. The task shown in Figure 2.3 aimed to stimulate students’ understanding that gas particles are in constant motion and are evenly scattered out in an enclosed space (diffusion of gases). In Meheut and Chomat’s study (1990), students were provided an opportunity to negotiate their ideas about the differences between properties of matter in solid, liquid, and gaseous states in terms of the intermolecular distances and the arrangement of particles (see Figure 2.4). In another activity, students first discussed the notion of sublimation and then represented two equal mass samples of iodine at the particulate level before and after sublimation (see Figure 2.5). This task allowed students to think about and understand the invariability of particles in different states, in other words, conservation of mass in a change of state.
Figure 2.3: The task of gaseous diffusion (Meheut & Chomat, 1990, p.275).
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Figure 2.4: The task of comparison of three states of matter at the particulate level (Meheut & Chomat, 1990, p.277).
Figure 2.5: The change of state (solid-gas) task (Meheut & Chomat, 1990, p.278). 46
Scott (1992) and Johnston (1990) tranferred the domain independent constructivist science teaching sequence proposed by Driver and Oldham (1986) to the context of the PNM. The modified form of the teaching sequence consisted of the following phases: a) orientation and elicitation of students’ ideas—where students were supposed to describe and explain some simple phenomena related to properties of matter, b) the nature of scientific theory and theory making—students were introduced to the nature of scientific theory making through discussion and simulations, c) a pattern of properties of solids, liquids and gases—students were encouraged to think about and find out the behaviors of solids, liquids and gases, d) theory making—students were allowed to explain their theories drawing upon the pattern of properties identified in the previous step, e) review, reflection and movement towards accepted theory—students were introduced to the kind of activities that help them move towards the school science view, f) application of accepted theory—students were given an opportunity to apply the theory they constructed about the PNM to a wide range of situations. To address students’ alternative conceptions concerning the motion of particles and the spacing between the particles, Johnston (1990) introduced students to a variety of demonstrations such as diffusion of gases, compressibility of gases. In doing so, students discussed their ideas in class and worked in groups to explain what happened at the particulate level as they experienced those demonstrations. In addition to class discussions, students also produced written artifacts, (e.g., posters, worksheets). Johnston (1990) acknowledged group discussions and “thought experiments” as useful in terms of encouraging students to consider the cases/questions such that there is nothing in the spaces between particles, why wood is solid rather than a liquid or a gas? 47
Scott (1992) investigated students’ conceptual pathways as they engaged in different classroom activities that created the context for learning the aspects of the PNM. In one case, students were asked to draw a picture of air in the closed flask after some of the air has been evacuated. The other activity was about relative compressibility of liquids and gases (see Figure 2.6), which involved the concept of the relative spacing between the particles in different physical states. To explore how students use particle ideas in explaining the behavior of solids, liquids and gases, Scott (1992) asked students to draw pictorial particle diagrams to show the arrangement of and the relative spacing between the particles in three states of matter. To address the concept of the motion of particles, gaseous and liquid diffusion were also demonstrated. Moreover, students individually performed a task of sketching out the structure of water. This final step of the teaching sequence offered evidence for the students’ ability to apply their prior experiences with the PNM to a new task. An earlier study by Nussbaum and Novick (1982) described an instructional approach that considers learning as cognitive accommodation of previously held alternative conceptions. The strategy consisted of three phases: a) exposing alternative framework—the phase that students were provided an exposing event and engaged in teacher-guided discussion, b) creating conceptual conflict—the phase that discrepant events, (e.g., half-evacuated gas filled flask and a syringe filled with as gas) were created to challenge students’ alternative conceptions, c) promoting cognitive accommodation— the phase that students shared their understanding of the events observed in the previous phase of instruction. During the discrepant event, students’ thinking was probed with questions such as “which part of the flask is left without air?” or “where do you place the 48
empty space (vacuum) in your model?” The purpose of the tasks was to offer students opportunities to become aware of the concepts that gas particles are uniformly distributed and they are in constant, continuous motion.
Figure 2.6: The task involves the distances between particles (Scott, 1992, p.209).
Singer et al. (2003) adopted a project-based science approach for teaching the aspects of the PNM. This instructional sequence consisted of four components: a) providing a context for the concepts being addressed, b) incorporating instructional technology to teaching science, c) constructing activities that permit students to employ multiple representations, d) sequencing the learning events in a way that students utilize their knowledge of the PNM in different contexts. The researchers addressed the five
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different aspects of the air, namely, composition of air, the arrangement and movement of particles in three physical states, the energy aspect of phases, and the nature of the particles themselves. To focus the students’ attention on the topic, the driving question, (e.g., “what affects the quality of air in my community?”) provided a context for understanding the underlying concepts of the PNM. In addition, “human models,” “gumdrop models” and visualization tool, (e.g., eChem) were used to teach the concepts of phase changes, atoms and molecules. Tsai (1999) adopted an analogy to address the four of students’ alternative conceptions concerning the aspects of PNM, namely, the size of, the arrangement of, the distances between and the motion of (static) particles. Students performed the analogical role-playing task in which they stayed in pairs (to represent the bromine molecule [Br2]) and acted as a group to present the conditions such as the arrangements of, the distances between and the motion of particles, when bromine changed its physical state with the increase of temperature. In the other studies, researchers pointed out the type of instructional approaches that they implemented, but did not provide the specific examples of activities to which students were introduced; for example, laboratory work followed with discussion (Haidar & Abraham, 1991), integrating (social) constructivist strategies (Johnson, 1998a, 1998b, 1998c; Kabapinar et al., 2004; Lee et al., 1993) and multiple representations (Bunce & Gabel, 2002; Gabel, 1993; Rohr & Reimann, 1998; Singer et al., 2003; Snir et al., 2003; Tasker & Dalton, 2006; Williamson & Abraham, 1995). The subsequent section, named teaching with multiple representations, discusses the studies that included the multiple representations as a teaching pedagogy. The following paragraphs talks about some of the 50
other studies, and the summary of all studies referred in this chapter regarding the research on students’ conceptual understandings of the PNM with or without instruction are included in Table 2.1 (see p. 55). Haidar and Abraham (1991) conducted a study with twelfth grade students to investigate how they at this grade level utilize their understanding of the PNM to explain the concepts of dissolution, diffusion, effusion and states of matter. The researchers examined students’ applied (everyday language) and theoretical (scientific language) knowledge of selected topics. They found that more than 40% of the students exhibited a variety of alternative conceptions about the PNM. The findings showed that the sources of alternative conceptions mostly emerge from students’ macroscopic reasoning and the instruction that they experienced. The researchers arrived at a conclusion that students’ reasoning abilities are highly associated with the use of the PNM. They also inferred from their results that students more frequently refer to the concept of the PNM in their explanations when they are probed to do so. Lee et al. (1993) examined sixth grade students’ conceptual understandings of the PNM as they evaluated the effectiveness of the curriculum unit that included activities to teach the particulate ideas. This unit consisted of a series of eight tasks concerning the nature of matter, three states of matter, expansion and compression of gases, thermal expansion, dissolving, melting and freezing, boiling and evaporation, and condensation. The results demonstrated that more than half of the students who involved in the activities showed sound understanding of the basic concepts of the PNM. Johnson (1998c) asserted that students develop the scientific views of the PNM if they are provided appropriate teaching-learning contexts. The teaching units created by 51
Johnson for this particular study were carried out within three years and engaged students in almost every aspect of the PNM through various activities. The data were collected through a cycle of interviews with students within three-year period (grade 7 to grade 9). To interpret the students’ understanding of the PNM based upon their interview responses, Johnson defined four distinct particle models. Model X refers to the understanding at which students conceive of substances as continuous. In the Model A, substance is regarded as continuous, but particles are embedded into other substance (raisin cake model). According to the third model, Model B, particles make up the substance but carry a macroscopic character. Model C characterizes the understanding where the particles are the substance, and the properties of the state are collective. Findings showed that about 60% of the students made progress toward a scientific understanding of the PNM. The data analysis revealed that the progress in students’ understanding of the PNM occurred in two dimensions: continuous to particulate and macroscopic to submicroscopic. Students, first, made progress through the continuousparticulate dimension, then, along the dimension of the macroscopic to collective.
Summary The instructional approaches adopted by researchers to address the common conceptual issues associated with the aspects of the PNM frequently offered opportunities to deepen students’ awareness about their alternative conceptions of the PNM. Researchers intended to move students toward the scientific views of the PNM through creation of cognitive conflict, inquiry-based projects, group discussions, written work, (e.g., posters, activity sheets, drawings), analogies or hands-on demonstrations.
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Students’ alternative conceptions are the product of their perceptions of the particles and are not created through direct experience/observation of the phenomena. Moreover, none of the instructional approaches/activities provided direct particulate experiences to the students but static particle models or submicroscopic simulations of the macroscopically observed phenomena. However, those instructional approaches aimed to involve students in controlled persistent observations about the macroscopic phenomena. Therefore, students made inferences about what happened at the submicroscopic level based on their observations. Students may have difficulty developing the particulate ideas by themselves if they know nothing or very little about particles. deVos and Verdonk (1996) drew attention to this issue and claimed that “teaching the particulate nature of matter in a scientifically meaningful way may be impossible without at the same time explicitly teaching [italics added] some of the rules of scientific explanation” (p.663). The trends in the instructional approaches used for research purposes to promote students’ conceptual understanding of the PNM indicated considerable associations with the contemporary views of learning. In the beginning of the 1980s, the conceptual change model (CCM) by Posner et al. (1982) with its educational implications was accepted by many to be a highly popular view of learning. The CCM required the creation of conceptual conflict with proper discrepant events in order to attain change in students’ alternative conceptions. In this respect, Nussbaum and Novick (1982) utilized the conceptual conflict as an instructional approach for teaching the aspects of the PNM. Then, the inquiry-based instruction was extensively recognized to be the best practices of teaching science among science educators with the release of the National Science 53
Education Standards (National Research Council [NRC], 1996). The incidence of observing the inquiry-based approach with multiple representations was no surprise in recently published studies (Bunce & Gabel, 2002; Singer et al., 2003; Snir et al., 2003). Consistent with the teaching ideas suggested in the major reform initiatives (American Association for the Advancement of Science [AAAS], 1993; National Research Council [NRC], 1996), the current study redesigned frequently used activities for teaching the PNM, (e.g., compression of gases, diffusion of food coloring [see Appendix A]), by integrating multiple representations as an instructional approach in the scientific inquiry context. Hence, the next section discusses the learning theories linked with multi-representational learning and the research involving multi-representational instruction.
54
% of Students w/ Scientific Conception
55
Data-Gathering Method(s)
States of Matter Addressed in the classroom
43.70%
Diagnostic test (Conceptual questions).
No specific instruction.
8% to 85%
Students’ drawings of air.
No specific instruction.
Not indicated
Not indicated
Solid, Liquid & Gas.
66
Not indicated
50.00%
30
Alternative conceptions concerning the structure of, the composition of, the size of, the shape of, and the weight of atoms/molecules.
Not indicated
GALT-Logical ability test; SAPAchievement test. GALT-Logical ability test; 12item multiple choice test. Semi-structured interviews.
Author
Participants
N
The Most Common Alternative Conceptions
Ben-Zvi et al. (1986)
10th grade students (Israel)
540
Benson et al. (1993)
2nd grade through university students
1098
Attributing physical properties (conductivity, color, malleability, physical state) to a single atom. Matter is continuous. Gases behave like liquids. There is relatively little space between gas particles.
Bunce & Gabel (2002)
10th and 11th grade students
447
Gabel (1993)
High school chemistry students
Griffiths & Preston (1992)
12th grade students
Not indicated.
No specific instruction.
Continued. Table 2.1: Summary of studies that examined students’ conceptions of the PNM with or without specific instruction.
55
Table 2.1 continued.
Participants
N
The Most Common Alternative Conceptions
% of Students w/ Scientific Conception
Haidar & Abraham (1991)
11th and 12th grade students
183
Not indicated
60%
Johnson, P. (1998a, b, c)
A cohort of students from 7th to 9th grade
36
52.70%
Johnston, K. (1990)
8th grade students
N/A
Matter is continuous. Difficulty in understanding the attractions forces between particles and the motion of particles. No vacuum exists between particles. Difficulty in understanding the relative spacing and the movement of particles in three states of matter. No vacuum exists between particles.
56
Author
Not indicated
Data-Gathering Method(s)
States of matter addressed in the classroom
Physical changes concepts test (PCCT), Test of Logical Thinking (TOLT). Periodic clinical interviews.
Solid, Liquid & Gas.
Audiotaping of teacher-student conversations, interviews with students, collecting students’ written products.
Solid, Liquid & Gas.
Solid, Liquid & Gas.
Continued.
56
Table 2.1 continued.
Participants
N
The Most Common Alternative Conceptions
Kabapinar et al. (2004)
9th grade students (Turkey)
23
Difficulty in making distinction between melting and dissolving.
Lee et al. (1993)
6th grade students
N/A
Meheut & Chomat (1990)
13-14 year olds
300
Matter is continuous. Attributing observable properties of matter to its single particles. Gases behave like liquids. Molecules expand when heated. No vacuum exists between particles. No vacuum exists between particles. Not being able to distinguish the relative spacing between particles in three states of matter and the motion of particles in three states of matter.
57
Author
% of Students w/ Scientific Conception
Data-Gathering Method(s)
States of matter addressed in the classroom
96.00%
Paper and pencil diagnostic test, interviews.
Solid and Liquid.
50%
Paper-and-pencil test that include multiple choice and short essay questions, interviews.
Solid, Liquid & Gas.
Not indicated
Students’ written artifacts, the tape recordings of the one-to-one interactions in class discussions.
Solid, Liquid & Gas.
Continued. 57
Table 2.1 continued.
58
Author
Participants
N
The Most Common Alternative Conceptions
Nakhleh & Samarapungavan (1999, 2005)
Elementary school (ages 7 to 10) and 8th grade students
15 & 9
Novick & Nussbaum (1981)
From 5th grade to college students
576
Nussbaum & Novick (1982)
7th grade students
N/A
Matter is continuous. Particles are small, but clearly visible like sugar crystals. Attributing macroscopic properties of matter to its single particles. Matter is continuous. No vacuum exists between particles. Particles are static. Expansion and contraction of particles with the change in the physical state of matter. Matter is continuous and static. No vacuum exists between particles.
% of Students w/ Scientific Conception
Data-Gathering Method(s)
States of matter addressed in the classroom
20% & 67 %
Interviews (Three interviews with each student).
No specific instruction.
30% to 80% depending on the given task.
Students’ drawings No specific and explanations on instruction. the given tasks.
Not indicated
Interviews, audiorecording of student discussions, students' written products.
Gas.
Continued.
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Table 2.1 continued.
% of Students w/ Scientific Conception
Data-Gathering Method(s)
States of matter addressed in the classroom
Two-questionnaires (Each include 12 tasks to explain everyday situations.) Pencil-and-paper test.
No specific instruction.
Not indicated
Knowledge Test, Pre and posttest.
Liquid and Gas.
Not indicated
Pre- and posttests, keeping a diary, audio taping small group sessions.
Solid, Liquid & Gas.
Participants
N
The Most Common Alternative Conceptions
Pozo & GomezCrespo (2005)
7th grade to university students
278
Particles are always stationary. Matter is continuous.
50% to 85%
Pereira & Pestana (1991)
From 8th to 12th grades students
227
Not indicated
Rohr & Reimann, (1998)
Not indicated.
6
Scott (1992)
8th grade students
N/A
No vacuum exists between particles. Particles are mostly static. Change in the size of the particles with the changing physical state. Matter is continuous. Particles are mostly static. No vacuum exists between particles. Matter is continuous. Uneven distribution of gas particles. No vacuum exists between particles.
59
Author
No specific instruction.
Continued.
59
Table 2.1 continued.
Participants
N
The Most Common Alternative Conceptions
Sequeira & Leite (1990)
8th and 9th grade students
182
Singer, et al. (2003)
7th grade students
900
Matter is continuous. No vacuum exists between particles. Particles are mostly static. Students are unaware of the existence of attraction forces between particles. Matter is continuous.
Snir, Smith & Raz (2003)
5th, 6th and 7th grade students
NA
Stavy (1988)
4th grade through 9th grade
120
60
Author
Matter is continuous. Size of particles change with the changing physical state. Air has no weight, Gases are lighter than liquids.
% of Students w/ Scientific Conception
Data-Gathering Method(s)
States of matter addressed in the classroom
33%
Written questionnaire, Interviews.
No specific instruction.
52%
40% to 90%
Gas Pre and posttests, a midterm quiz, air drawings, interviews, video recordings and field notes. Interviews Solid and Liquid
Not indicated
Interviews
Liquid and Gas
Continued.
60
Table 2.1 continued.
Participants
N
The Most Common Alternative Conceptions
Stavy (1990)
4th grade through 9th grade
120
Tasker & Dalton (2006)
First year chemistry students (Three different groups)
22, 30 & 48
Williamson & Abraham (1995)
College General Chemistry students
124
Matter exists when there is evidence of its existence. Weight change with the change in the state of matter. Difficulty in distinguishing the patterns in the arrangement of and the distances between the particles. Attributing physical properties of matter to single particles. Matter is continuous. No vacuum exists between particles. Particles are mostly static. Students are unaware of the existence of attraction forces between particles. Difficulty in distinguishing the patterns in arrangement of and distances between the particles.
61
Author
61
% of Students w/ Scientific Conception
Data-Gathering Method(s)
States of matter addressed in the classroom
Not indicated
Interviews
Liquid and Gas
Not indicated.
Pre- and posttest, Interviews.
Solid and Liquid
About 80% motion of particles. About 55% nothing among particles.
TOLT – Reasoning test, PNMET – Content test.
Solid, Liquid and Gas
Teaching with Multiple Representations Today, educators are urged to create multi-representational learning environments on account of its promise to improve student learning in science classes (Ainsworth, 2006). Two benefits of using multiple representations as a teaching pedagogy claimed to be cognitive and affective (Ainsworth, 1999). Multiple Representations (MRs), [e.g., a mixed set of verbal (written or oral) and pictorial (static pictures, animations or student generated drawings)], not only have the potential of capturing students’ attention to the concepts to be taught but also support their conceptual understandings in a certain domain (Ainsworth, 1999). Hence, an apparent reason for believing in the significant role of multiple representations in student learning resides in the idea that students receive large benefit from their learning when they are interested in the topic at hand and presented with the ways that are pertinent to their learning preferences. Ainsworth (1999; 2006) articulated three functions of the use of multiple representations. The most evident one is that MRs provide diverse opportunities to students in constructing the same knowledge from multiple perspectives, thus, any weaknesses coupled with one particular representation could be replaced by another one. The second one is that one form of representation may facilitate the interpretation of the other abstract or more complicated representation so that students’ understanding of the unfamiliar representation is constrained by utilizing the inherent characteristics of the familiar one. Moreover, MRs help students generate a deep understanding of a domain, if students are explicitly taught about the associations among the representations, and thus an abstract concept becomes more concrete and meaningful to them.
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Moreover, Pozzer and Roth (2003) developed an abstraction continuum that displays the multiple ways that scientists frequently use in representing natural phenomena (see Figure 2.7). The ones shown in italic in Figure 2.7 are the forms of representations that were incorporated into the instructional interventions designed for the current study. Observing the actual phenomenon, (e.g., video clips of experiments) was placed at the less abstract end of the continuum. However, it should be noted that unlike scientists in many other fields, chemists use representations to illustrate “unseen entities and processes” that occur during the course of chemical inquiry (Kozma et al., 2000, p.107). Therefore, just seeing the video recording of or directly observing the actual chemical phenomena would not be sufficient to explain/or model the governing processes of the phenomena. Whereas the professional chemists tend to employ more abstract means situated at the right end of the continuum, multiple visual representations— animated video clips of chemical phenomenon at the submicroscopic level and static particle models—potentially make more sense to students in their efforts to comprehend the structures and principles that control the occurrence of the chemical phenomena (Myers, 1990).
Less abstract More detail World Observing
More abstract Less detail Photos
Sketches
Diagrams Maps, Model
Figure 2.7: Abstraction continuum (Pozzer & Roth, 2003).
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Graphs Tables
Equations Text
Mayer (2001) defined multi-representational learning as “learning from words and pictures” (p.3). In his definition, words stand for verbal representations in written or oral form, whereas pictures signify pictorial representations such as maps, diagrams, illustrations, photos, animated videos and so on. In the present study, verbal forms of representations include students’ oral and written explanations of the given physical phenomena at the macroscopic and the particulate level. The pictorial forms of representations entail student-generated drawings that depict the submicroscopic behavior of the physical phenomena, the online animations at the submicroscopic level and the available static particle models as a reference to scaffold students in generating submicroscopic pictorial representations of matter. The meaningful learning through multiple representations occurs when students construct a coherently linked knowledge frameworks. There are several cognitive perspectives that explicate the processes and usefulness of multi-representational learning: Dual Coding Theory (Paivio, 1986), Cognitive Theory of Multimedia Learning (Mayer, 2001, 2003) and Cognitive Load Theory (Chandler & Sweller, 1991; Sweller & Chandler, 1994). The following sections discuss the theoretical foundations of the each one of these multi-representational learning perspectives.
Dual Coding Theory Paivio’s dual coding theory establishes a sound theoretical basis for explaining how verbally and pictorially presented knowledge is integrated into students’ knowledge framework. According to dual coding theory (Paivio, 1986), the external knowledge activates one (or both) of the two distinct systems in the human memory: verbal and 64
nonverbal. The verbal system is responsible for representation and processing of knowledge that involves language. The nonverbal system is specialized for processing of knowledge associated with images, which may either be internal (mental images) or external. These two systems are structurally different, because each has individual representational units (codes) in specific modes, namely the logogens and the imagens. The logogens correspond to word-like codes, whereas the imagens are visual codes of the natural phenomena. Imagens allow the creation of mental images that carry the properties of actual phenomena and lead to dynamic transformations, which is not the case with the logogens. These representational codes are organized in two distinct ways. Imagens are considered to be existing “in the form of holistic sets with information available for processing in a synchronous or parallel manner” (Sadoski, Paivio, & Goetz, 1991, p.473). Logogens, however, are structured as discrete large successive codes so that verbal system processes a limited chunk of knowledge at a time (Vekiri, 2002). In addition, the associative links within each system internally connect the mode specific representational units (codes). Despite the functional independence of two systems, verbal and nonverbal systems are, indeed, interconnected. Thus, they are able to function “independently, in parallel, or in an integrated manner” (Sadoski et al., 1991, p.473). Referential connections establish between verbal and visual systems, enabling the conversion of one form of knowledge into another. However, these relations between two systems are not always one-to-one (Sadoski et al., 1991), because verbal representation may evoke more than one image or not at all. The same holds true for the transformation visual information to the verbal one. 65
Clark and Paivio (1991) emphasized the value of dual coding in student learning, stating that “additive effect of imagery and verbal codes is better than a verbal code alone” (p.165). This implies that visually enhanced instruction enables students to experience the knowledge in both verbal and nonverbal form. Hence, students have multiple accessible paths to retain and retrieve the knowledge they are exposed to, because of double encoding during instruction. Visuals contribute to the learning by making the abstract more concrete to students. In fact, concrete makes more sense than abstract and increases the probability of constructing referential associations between the two modality specific codes, namely imagens and logogens (Clark & Paivio, 1991)
Cognitive Theory of Multimedia Learning Some constituents of cognitive theory of multimedia learning demonstrate features similar to Paivio’s dual coding theory (Mayer, 2001). Mayer’s theory has three underlying assumptions: dual channels, limited-capacity and active processing. The pictures and words from external sources are detected through either eyes or ears in the sensory memory. The printed materials and pictures are registered by eyes— visual/pictorial channel, while oral materials are registered by ears—auditory/verbal channel. These two channels select registered pictures and words and transmit them to the working memory. However, the amount of knowledge processed within each channel is very limited such as about a sentence of the narration and about 10 seconds of the animation at a time (Mayer, 2003). The received selected knowledge is actively processed in the working memory. Working memory either directly organizes the incoming words and images as verbal and pictorial representations or turns either one 66
into the other form of representation, (e.g., words into pictures and/or vice versa) to be further processed in a different channel. After the set of selecting and organizing processes, students mentally build a verbal and/or pictorial representation of the real phenomena. Then, the connections are built between the mental verbal and pictorial representations, comprising the existing prior knowledge from long-term memory, which is called integrating. These working memory processes take place in an iterative manner as opposed to in a linear sequence (Mayer, 2003). Cognitive theory of multimedia learning holds the equivalent educational promises as dual coding theory does. Mayer (2003) contends that “students learn more deeply from a multimedia explanation presented in words and pictures than in words alone” (p. 131). Mayer justifies his claim about the positive impacts of multimedia instruction on student learning by offering both numerical and descriptive reasons. The extent of knowledge delivered on two channels is more than the one channel. Therefore, students have twice as much chance to interact with the knowledge that they are taught. Moreover, words and pictures communicate distinctive but complementary traits of the same fact. This facilitates the building of associative representations in learners knowledge framework, leading to meaningful learning (Mayer, 2001).
Cognitive Load Theory Sweller & Chandler (1994) maintained that learners have a limited working memory but a very efficient long-term memory that is able to keep an immense amount of knowledge as schemas, which are defined as “a cognitive construct that organizes information according to the manner in which it will be dealt” (p.186). According to 67
Sweller and Chandler, some kind of knowledge or task could appear to be harder to learn than others. This is not due to the fact that each constituent of the knowledge is harder to incorporate. However, there may be numerous constituents that need to be processed by working memory and incorporated into long-term memory in a fairly short amount of time. Additionally, each constituent usually can not be learned in isolation but must be learned simultaneously with its other constituents. Thus, knowledge that contains a large number of associative constituents overburdens individuals’ limited processing capability because of its excessive cognitive demand. Sweller and Chandler (1991) suggested the split attention effect as an instructional approach to alleviate possible cognitive load in learning complex concepts. Multiple linked representations, in that regard, are functionally in line with this suggestion. According to Mayer and Moreno (1998), presenting the content through verbal (auditory) and visual (pictures or written text) representations reduces the load in each processing channel in working memory. This is because “when learners … concurrently hold words in auditory working memory and pictures in visual working memory they are better able to devote attentional resources to building connections between them” (p.318). Consequently, this vastly contributes to student learning in terms of providing a wealth of knowledge with an integrated manner and with lowered cognitive load. The overview of multi-representational learning theories of dual-coding (Paivio, 1986), cognitive multimedia (Mayer, 2001) and cognitive load (Sweller & Chandler, 1994) was surveyed to understand how students learn when they engage in the multirepresentational instruction. The following section focuses on the research concerning how multi-representational instruction contributes to student learning of science. 68
Research on Multi-Representational Learning The research that examines the use of the multi-representational instructional pedagogy is divided into two lines with regard to the kinds of media that they utilize in promoting student learning: computer-based multimedia and student-generated drawings. Computer-Based Multimedia The researchers from two interrelated fields, (e.g., psychology and education) investigated the outcomes of multi-representational learning theory in the actual settings. The research by psychologists usually conducted outside of classroom with college students. For instance, Moreno and Valdez (2005) divided 98 undergraduate students into six different treatment groups with varying interactivity and multi-mode representations, (i.e., interactive word and pictures). Each instruction included computerized multimedia presentations on the processes of lightning. Students were tested on retaining, transferring and difficulty of the introduced content. The results of multivariate analysis revealed that regardless of the assigned interactivity modes, students in the group of word and pictures outperformed students in the group of word alone or picture alone concerning the transfer and retention of the learned knowledge. The difficulty ratings for the presented material were high for students in both picture alone groups. The researchers concluded that multimedia learning environments should combine verbal explanations with visual representations in teaching science concepts. The results of the studies with similar experimental situations were consistent with Moreno and Valdez’s study (Mayer, 2003; Mayer & Anderson, 1991, 1992; Mayer & Moreno, 1998). Lewalter (2003) looked into the effects of incorporating dynamic and static visuals in an expository text on students’ learning outcomes and the types of learning 69
strategies used while students were introduced to those visuals. A total of 60 undergraduate students were assigned to one of the three forms of the computer-based learning text, two illustrated texts with either dynamic or static visuals, and text only form. A significant difference was reported between two visually enhanced groups and text only group regarding factual knowledge. No significant differences were evidenced between the students in dynamic and static visual groups on any of the following areas of interest: factual knowledge, comprehension and problem solving. Thus, Lewalter asserted that static visuals are equally superior as dynamic visuals for assisting student learning. Hegarty (2004) claimed that “there should be an advantage of dynamic over static media, especially for teaching students about dynamic phenomena”(p.344). However, there is no strong evidence that supports the success of animated representations in all learning situations (Hegarty, 2004; Tversky, Morrison, & Betrancourt, 2002). Bodemer et al. (2006; 2005; 2004) tested the impacts of interactive integration of multiple representations over presentations of information in interactive with nonintegrated format in different science related contexts. The researchers found that students with low prior knowledge failed in the task of interactively relating the diverse sources of representations to one another, and therefore received almost no or little benefits from the learning experience provided to them. Moreover, students who had adequate prior knowledge about the content were capable of identifying unique features of unfamiliar pictorial representation and relating to textual forms of representation. Consequently, the nature of the content to be learned and prior knowledge were identified to be two main factors that greatly influence the degree of integrating multiple representations of the phenomenon in a meaningful manner by students. 70
The researchers in the field of education put the theory of multi-representational learning into practice in the K-12 and college classrooms for teaching specific science concepts. For example, Kozma et al. (1996) used a software called, 4M:Chem, with two classes of college chemistry students during two one-hour lectures as a multirepresentational visual aid in teaching the topic of chemical equilibrium. The instructors frequently showed and referred to multiple views of chemical equilibrium with verbal explanations to direct students’ attentions to the topic and make connections among the representations. Students who attended these lectures scored significantly better on the posttest, and 50% of students developed a scientific understanding of chemical equilibrium after the instruction. Similarly, Wu et al. (2001) designed a computer-based visualization tool, eChem, based on Kozma and Russell’s (1997) argument about the existing need for encouraging oral and written discourse among students to help them develop meaningful conceptual connections between representations. eChem was the software that displayed different chemical compounds in multiple forms as well as allowed students to construct their own molecular models while engaging them in discussions about underlying concepts of the representations. Eleventh grade students interacted with eChem for a six-week period. Based on the pre and posttest outcomes, a significant knowledge gain was observed in students’ understanding of the chemical representations. The findings of similar studies that took place in middle school through college classes were consistent with the studies reported by Kozma (1996) and Wu (2001), favoring the use of computer-based multiple representations over standard instructional formats while teaching a variety of chemistry
71
concepts such as chemical reactions and electrochemistry (Ardac & Akaygun, 2004, 2005; Schank & Kozma, 2002; Yang & Andre, 2003). To date, five research studies, those published in prominent science education journals, used multiple representations either through computerized instruction (Rohr & Reimann, 1998; Snir et al., 2003; Tasker & Dalton, 2006; Williamson & Abraham, 1995) or presentation of static particulate models (Bunce & Gabel, 2002) to assist student learning of the aspects of the PNM. Williamson and Abraham (1995) conducted an experimental study by using particle animations in two treatment situations: as a lecture supplement and as both the lecture supplement and an individual activity. The instruction took about four weeks, and the length of time that animations were shown was 18 minutes for eleven different animations. The results showed significant improvement in both treatment groups’ conceptual understandings of the PNM compared to control group. Almost all students in the treatment group perceived matter as discrete particles following the instruction, whereas 23% of control group students still held onto the continuous view of matter after the instruction. About 80% of the treatment group students developed a scientific understanding of the motion of particles. Additionally, about 55% of the students in the treatment groups believed in the existence of vacuum among particles of matter. Rohr and Reimann (1998) reported two case studies for students from two instructional situations: text and pictures and text and animations. Their findings did not suggest a significant overall instructional effect in favor of pictures or animations due to having a small sample and limited data, but the authors still considered animations as potentially useful for helping students develop the scientific views of the PNM. However, 72
they were cautious about their assertion, due to the situation that “enormous cognitive load involved in mentally simulating the dynamic behavior of particle systems” (p.65). Snir et al. (2003) designed a software tool to help students’ develop an understanding of particulate models at the same time as learning the aspects of the PNM. The phenomena of mixing alcohol and water, thermal expansion of metal ball and combining copper and sulfur were selected as the contexts to address the diverse aspects of the PNM. The software provided students opportunity to observe the actual phenomena at the virtual settings as well as compare the capability of the given models in terms of how well they account for the actual phenomena at the submicroscopic level. Sixty percent of the students who interacted with the software spontaneously generated proper explanations at the submicroscopic level. Forty percent of the students offered both scientifically accepted particle model drawings and explanations for all three of the phenomena. Snir et al. also followed up the same group of students a year later for longterm retention of the concepts. Thirty percent of the students were able to sustain their scientific understandings of the PNM. The researchers argued that even if 7th graders are conceptually ready to comprehend the particle ideas, it is better to wait for teaching the particle ideas until they develop a strong macroscopic understanding of the matter. Tasker and Dalton (2006) designed an instructional approach that uses the visual tool, (e.g., VisChem) along with constructivist pedagogy. In this learning experience, students observe a chemical phenomenon; document their observations in various forms such as words, diagrams and so on. Afterwards, students describe the phenomenon in words and draw a pictorial representation of what happened at the particulate level that accounts for their observations. They, then, discuss their representations with their peers, 73
and the instructor guides them in their effort to generating explanations and representations by focusing their attention on the certain features of the phenomenon. Subsequently, students view a computerized animation that simulates the observed phenomena. The follow-up tasks in this learning pedagogy consisted of reflecting on any similarities and differences between the animation and students’ own drawings, relating the particulate representation to the symbols, (e.g., equations, formulas) and adopting their understanding of the phenomenon to a similar phenomenon. The authors claimed that this particular visually enhanced constructivist learning design provide students environment to develop scientific molecular-level mental representations, which are “multi-particulate, dynamic, interactive and three-dimensional” (p.146). Bunce and Gabel (2002) used static particle models in teaching such curriculum units as states of matter, solutions, bonding and stoichiometry. Students in the experimental group were allowed to explore given phenomena using three representations of matter, (e.g., macroscopic, submicroscopic and symbolic). However, control group students just experienced the macro and symbolic representations of matter. The results showed significant improvement in students’ achievement scores across all the units in favor of the experimental group. The results of the study suggested that visual representations of the chemical phenomena have a significant impact on students learning as to helping them building the internal connections among the key components of the introduced concepts. Student-Generated Drawings No large body of empirical research exists to offer evidence for how studentgenerated drawings serve as an instructional strategy in students’ learning of science 74
(Edens & Potter, 2003; Hall, Bailey, & Tillman, 1997; Van Meter, 2001; Van Meter, Aleksic, Schwartz, & Garner, 2006). The extensive review of literature by Van Meter and Garner (2005) suggested several practical reasons to utilize drawings as part of multirepresentational learning, all of which has potential to initiate the empirical research in this field, such that student-generated drawings: • • • •
enhance students’ observational processes in science learning. focus students’ attention on visuals as reinforcing the knowledge gain. prompt the dialogue and writing processes. increase students’ attitudes to the intended content, involving them in higherorder thinking. Van Meter and Garner (2005) proposed a theoretical framework for the processes
of drawing construction, called Generative Theory of Drawing Construction. Their theory derived from Mayer’s cognitive theory of multimedia learning (Mayer, 2001). Three cognitive processes presumably facilitate the occurrence of learning from drawings: selection, organization and integration (Van Meter & Garner, 2005). The Generative Theory of Drawing Construction was based on the assumption that students build their drawings just by relying on textual knowledge. Thus, students select key elements of the given phenomena from the verbal representation. They then retrieve relevant internal nonverbal representations of the phenomena from the prior knowledge, and then mentally organize selected imagery in the light of verbal representations. When drawing, students both externally organize their nonverbal representation of the phenomena and mentally integrate the verbal and nonverbal representations. The advantage of student-generated drawings over the computer-based representations comes out at the phase of integration. This is because the overlap or discrepancy between the constructed drawings and the verbal representations provide evidence for the nature of students’ understanding of the 75
concepts to be learned. Their drawings may reflect either scientific or alternative conceptions developed by students (Hall et al., 1997; Van Meter & Garner, 2005). Van Meter and Garner (2005) mentioned that without support, “not only may the learner fail to detect inaccuracies in understanding, even detected ones may go uncorrected. These uncorrected comprehension errors are passed on to the nonverbal representation and, ultimately to the mental model responsible for … higher order thinking” (Van Meter & Garner, 2005, p.319). Moreover, providing effective instruction is considered to be of great importance to facilitate students’ learning of abstract concepts. When students’ awareness of the critical aspects of the given phenomena rise with appropriate instruction, they better select and organize knowledge pieces in their representational picture (Alesandrini, 1984; Van Meter & Garner, 2005). In an early study by Alesandrini (1981), college students were asked to either draw pictures or write paraphrases of the given chapter about electrochemistry. Students in the control group, however, read the chapter twice. Students who drew pictures to express their understanding of the concepts performed better on the posttest than students in other treatment situations. Hall et al. (1997) examined the effectiveness of the studentgenerated drawings and instructor-provided representations over instructor-provided textual representation while testing the improvement in students’ scientific explanations of how an air pump works. Results revealed no significant difference between the two groups that students either inspect the pictures or draw their own. Van Meter, Aleksic, Schwartz and Garner (2006) separately assigned students from two different grade levels to four different instructional conditions: non-draw, draw, illustration and prompt. In these conditions all students interacted with both pictorial and textual representations, but 76
given support in generating a drawing increased from draw to prompt situation. The results confirmed that student-generated drawings as a learning pedagogy are more promising than instructor-provided representations. Additionally, support was proved to be the critical factor to improve student learning through their own pictorial drawings of the concepts to be learned. In Van Meter et al.’s study, students (in prompt situation) who read, drew, and inspected provided illustration and compared their own drawing to provided illustrations by answering the guided questions achieved better scores on the posttest than did students who drew without support (draw). Conclusion Students’ conceptions of natural phenomena that are inconsistent with the scientific views have already been well documented in the science education literature, including the particulate nature of matter. Researchers gave particular interest in students’ alternative conceptions and developed a range of theoretical frameworks to model the processes of how conceptual change occurs in students’ conceptual frameworks. These theoretical perspectives suggest that conceptual change is a sophisticated process and is less likely to be accomplished with traditional instruction. In other words, alleviation of students’ alternative conceptions of the natural phenomena requires special treatment/effective instructional interventions. In that sense, multi-representational learning theories, (e.g., dual coding theory, cognitive theory of multimedia-learning and cognitive load theory) and empirical research on multiple representations acknowledge the effective role of multirepresentational instruction on student learning of science concepts. However, just a few 77
studies have been conducted in actual classroom settings in an attempt to explore the effectiveness of the multi-representational instruction, particularly students’ own drawings (Tasker & Dalton, 2006), in students’ scientific understandings of the PNM. The current study not only tested the efficacy of multi-representational instructional approach on stimulating change in students’ conceptual understandings of the PNM, but also looked at the extent to which multi-representational learning reinforces the durability of students’ scientific understandings of the PNM. In addition, only two studies (Johnson, 1998c; Snir et al., 2003) longitudinally explored the variations in students’ conceptual understandings of the PNM. The current study intended to characterize the nature of high school students’ conceptual pathways of the PNM from the pretest to the post to the delayed posttest as they experience the multirepresentational learning. Identifying and describing the patterns in students’ conceptual pathways of the PNM offer a complete portrait of student learning that occurs in multirepresentational learning environments. The current research has the potential to fill the existing need for longitudinal studies.
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CHAPTER 3 METHODS AND PROCEDURES Introduction The current study primarily explored the effect of the Reform-Based Teaching with Multiple representations (RBTw/MR) and the Reform-Based Teaching (RBT) instruction on promoting changes in high school students’ conceptual understandings of the PNM and sustaining their scientific understandings over an extended period of time. The subsequent goal of the study was to characterize the patterns of individual students’ conceptual understandings of the PNM from before beginning the instruction to shortly after completing the instruction to three-months after completion of the instruction. This study also intended to examine the overall variations in each group of students’ conceptual understandings of each particular concept that constitutes the particulate theory of matter. Hence, the following five research questions guided this quasiexperimental research study: (1) What are the types of conceptual understandings held by high school students about the aspects of the PNM just before, immediately after, and three-months after completion of the RBTw/MR and the RBT instruction?
79
(2)
How does the conceptual understanding of high school students on the aspects of the PNM change from preinstruction to post and to delayed posttest administered three-months after completion of the RBTw/MR and the RBT instruction?
(3) How do high school students’ types of conceptual understandings of the PNM differ immediately after, and three-months after completion of the RBTw/MR and the RBT instruction? (4)
How do the two groups compare just before, immediately after, and three-months after completion of the RBTw/MR and the RBT instruction?
(5) What are the conceptions held by high school students about each scientific aspect of the PNM just before, immediately after, and three-months after completion of the RBTw/MR and the RBT instruction? The Pilot Study The preparatory work for the current study started a year before designing this study. In doing so, the researcher attended a chemistry teacher’s classes in a local high school three times per week for three hours each day from the beginning of February through the end of May in the year of 2004. The observations in those classes helped the researcher become familiar with the classroom culture in the U.S. schools. In addition, the classroom observations provided the researcher an opportunity to gain insights into students’ ideas about chemistry concepts and the kinds of instruction typically used in teaching the abstract concepts of chemistry. When the design of the current study was completed about a year after attending and observing the classes, the researcher met the same teacher to discuss instructional 80
pedagogies and each one of the activities developed for the present study. During a threehour long meeting, based on her experiences with the students, the teacher (Mrs. E.) provided some feedback as to how the designed activities might work in actual classroom settings. She also offered suggestions about the wording of the questions on activity sheets and appropriateness for 11th grade students. Following the meeting, the researcher made revisions on student activity sheets and the instructional sequences in the light of Mrs. E.’s suggestions. Even though the researcher and Mrs. E. made a commitment in May of 2005 to conduct this study in her classes in the autumn of 2005, this would not come true due to change in her teaching responsibilities by her school’s administration. Another teacher (Ms. M.) from the same school volunteered to implement the instructions of the RBTw/MR and the RBT in her classes in the beginning of the new academic year. At the time when the researcher met Ms. M., she was in charge of teaching chemistry during the summer school in the summer of 2005, which allowed for the instruction of the RBTw/MR to be pilot tested with a group of students who were enrolled in the class. The researcher was present in the summer school class to observe the flow of the instruction in an actual setting and to record the issues that required changes on the activity sheets and the instructional sequences. The questions on the student activity sheets and the instructional sequences were modified after pilot testing the RBTw/MR instructional intervention with the summer school students. However, just before 2005-2006 academic year started, the introductory chemistry classes that Ms. M. would be teaching were taken from her. Then, the researcher started recruiting the chemistry teachers to participate in the study. Ms. B. 81
from another school in the same school district was willing to implement the instructions of the RBTw/MR and RBT in her classes. Before starting the interventions, the researcher discussed the instructional pedagogies that would be practiced in each group and the activities with Ms. B. In addition to designing the instructional sequences and the activity sheets, the researcher devised an open-ended questionnaire as an assessment tool to be used in the current study. Two chemistry experts checked the content and the wording of the questions before pilot testing the questionnaire with the 43 students in Mrs. E.’s classes in the spring of 2005. The purpose of the pilot test was to analyze the questionnaire items for their clarity and suitability for high school students. Minor modifications were made on the wording of the questions in the questionnaire with regard to the outcomes of the pilot test data. For example, on the pilot test, several students asked questions about the statement that referred to the picture that shows the gas state at the particulate level. The statement follows: “here is a stoppered flask containing particles of a gas.” Since the statement did not specify the name of a gas, students wondered if the flask contains air or not. After the pilot test, the statement was rephrased as “first a flask is evacuated. Then, the flask is filled with oxygen gas” (see Appendix C, question 10). The pilot data were not included for analysis of the current study. Also, the results of the pilot study were not reported in this dissertation or any other venue. Rather, the pilot data were used for the purposes of identifying confusing points with the questionnaire items and adjusting those points before administering the questionnaire to the participants of the current study. The framework of the instructions and the development of questionnaire are further discussed in more detail in the subsequent sections in this chapter. 82
Research Design The nature of the research questions shaped the research design of the current study, which involved comparison of the two instructions. This study compared the RBT and RBTw/MR instruction with regard to the extent of change in students’ conceptual understandings of the PNM and the durability their scientific understandings constructed during the instructional phase. In this context, students in both groups engaged in the in the same activities with the same sequence of experiences (see Appendix A). Yet, the instruction of the RBTw/MR differed from the instruction of the RBT in terms of the frequency of using the multiple representations in relationship to the macroscopic phenomenon and the likely actions that occur at the submicroscopic level. The framework for these two particular instructions will be articulated in the subsequent sections in this chapter. Moreover, the nature of the first research question required identifying the types of conceptual understandings of the PNM held by high school students who received the RBT and the RBTw/MR instruction. For the current study, the types of conceptual understandings can be defined as descriptive labels that indicate the degree to which students conceptually understand the constituent concepts of the PNM. Students’ ability to consistently apply the concepts of the PNM to different contexts was critically considered while identifying the participants’ types of conceptual understandings. Identifying the types of conceptual understandings of the PNM for each student in a descriptive manner at different moments in time (before, immediately after, and three months after the intervention) provided evidence for the portrayal of individual students’ conceptual pathways as well as thorough examination of the effectiveness of two 83
different instructional interventions. Thus, this study was a quasi-experimental (Campbell & Stanley, 1963), control group design with a pretest, posttest, and delayed posttest. Participants and Context of the Study The study was conducted in two classrooms of a comprehensive four-year high school, which included grades 9 to 12 and was located in a suburban area of a large city in the Midwest part of the United States. By the time this study was conducted (20052006 academic year), the total enrollment at the high school was 1586 students. The high school required students to complete at least three credits of science for graduation. The student population was fairly homogenous, with 80% of the school population being white and 20% of the students coming from various other ethnic and racial backgrounds. The socioeconomic statuses of most students’ families were middle and upper class in this school, based on the data from a non-profit research organization (Community Research Partners [CRP], 2005), which reported that about 17% of the students in this school were eligible for free and reduced lunch. The participants of the study were enrolled in one of the two introductory level chemistry classes taught by the same teacher. A total of 47 introductory chemistry students in the two classes agreed to participate in this study. All participants and their parents/guardians signed consent and assent forms (see Appendix D) in order to participate in the study. However, 5 of the 47 students (three from the RBTw/MR group and two from the RBT group) were dropped from the study because these students were absent when the tests were administered in the classes. Three of five students did not take the pretest, and the other two students took neither the posttest nor the delayed posttest. 84
One of the two classes was randomly assigned for the RBTw/MR group by the researcher, and the other class received the RBT instruction. The RBTw/MR group of 23 eleventh graders contained 12 male and 11 female students. The RBT group of 19 students included 11 males and 8 females. Students in the RBT group also were all in the eleventh grade with the exception of one student who was in the twelfth grade. Both groups consisted of 16 and 17 year-old students, with the average age of 16.5 years. None of the students in either group had previously taken either physics or chemistry, but they had completed freshmen physical science. All of them had taken at least one life science course, (e.g., biology, environmental biology, cell biology). Students’ self-reported science grades in previous years in the high school are considered to be an indicator of students’ achievement in science. The results of the t-test showed that there was no significant difference between the two groups in terms of students’ science achievement (t = 1.702, p > 0.05). Table 3.1 summarizes the classroom demographics for both groups.
Group
N
Male
Female
Grade 11
Grade 12
Average Age
RBTw/MR
23
12
11
23
0
16.5
RBT
19
11
8
18
1
16.5
Table 3.1: Demographics of the RBTw/MR and the RBT groups.
The teacher who implemented the two instructional interventions had four years of experience in teaching science. She had taught different high school science classes 85
such as physical science, biology, and chemistry. Her undergraduate major was in physical education, and she had a comprehensive teaching certificate for teaching chemistry and life sciences. As part of her typical teaching practices, she used hands-on experiments, demonstrations, and group work. In her classes, students were working in pre-assigned groups of 2-3 to perform experiments, and they were writing lab-reports or other assignments (e.g., journal writing) individually. Both of her classes were scheduled to meet for 47 minutes five times per week. The RBTw/MR group met at 7:25 a.m. (the first period), and the RBT group met at 11:20 am (the fifth period). The Framework of the Instructional Interventions Two types of instructional interventions were developed for the present study. Both interventions were consistent with the teaching pedagogies proposed by the National Science Education Standards (NRC, 1996). They were both exemplary instructional interventions that differ from the traditional views of teaching and learning of science in such a way that both interventions intended to encourage students to inquire about the probable processes of each given phenomenon at the submicroscopic scale. These two instructional interventions also put emphasis on social interactions among students, and between students and the teacher through small-group work and wholeclass discussions. The primary purpose of both interventions was to create a learning environment that allowed student involvement in the change of knowledge. Both interventions lasted twelve class periods and also aimed to address students' alternative conceptions of the PNM and to accomplish the content goals specified by the National Science Education Standards and the Benchmarks for Science Literacy. 86
One of the instructional interventions was called Reform-Based Teaching with Multiple Representations (RBTw/MR). The instruction component of the RBTw/MR contained three dimensions: inquiry, written and oral discourse, and multiple representations. In the inquiry context, students predicted, observed, and questioned the natural phenomena, (e.g., the dissolution of potassium permanganate, mixing of water and alcohol [see Appendix A]). Social constructivist perspectives on student learning point to the critical role of interactions between peers and whole-class discussions in student meaning making (Driver, 1995; Wu, 2003). As students inquired about the submicroscopic occurrences of each phenomenon, they shared and negotiated their reasoning/theories with their peers within small groups first. Based on their macroscopic observations, each group of students was asked to generate an explanation for what happen at the submicroscopic level and to draw particle models to represent the occurrences of macroscopically observed phenomena in different time intervals at the particulate level. The RBTw/MR instruction was intended to engage students not only in oral discourse but also in written discourse (Prain, 2006). Activity sheets were provided to each student during each activity to record their observations as well as to communicate their individual reasoning about each phenomenon verbally through writing and pictorially through drawing of submicroscopic representations for the observed phenomenon (see Appendix B). Each activity sheet included the static particle models of matter for the three states of matter along with the relevant background information. The pictorial and verbal information was provided to assist students' thinking in generating their own explanations and pictorial particle model representations for the macroscopically observed phenomena (Van Meter et al., 2006). In addition, during 87
almost every class period the static particle model transparency (the same models as in students’ activity sheets) was projected on a screen at the front of the classroom to be used as a visual reference during small group or whole-class discussions. After small group discussions, each group presented their explanations and the pictorial particle model representations of the observed phenomena to the class. During these presentations, the teacher sometimes stopped the presenters and asked questions about certain issues with their drawings/explanations to clarify ambiguity in their explanations and learn the reasoning behind the pictorial representations that they came up with for the observed phenomena. When needed, the teacher also guided students through questioning about certain aspects of their pictorial representations, intending to improve their pictorial representations and verbal explanations of the phenomena. The teacher also encouraged the students in the class to share their agreement or disagreement with what was just presented along with their own reasoning. The teacher sometimes asked students (either individual groups of students or the whole class) to redraw their pictorial particle representations or to revise or rewrite their explanations for what happened at the particle level for the observed phenomena following the whole-class discussions. For the three cases, namely, dissolving of a solid in water, motion of particles in the three states of matter, and diffusion of gas particles, students in the RBTw/MR group were provided opportunities for seeing the online simulation of these macroscopically observed phenomena at the particulate level. The same animation clips were run a couple of times by directing students’ attention to the important aspects of the animation. The animations used for the current study are available on the world-wide web, and the snapshots of these simulations can be seen in Figure 3.1 and Figure 3.2 (see Appendix A). Following each 88
activity students were asked to write down a one-page hand-written journal by responding to six prompts (e.g.; a) What was this activity about? b) What do you know about it right now? c) Were there things that confused you? d) Were there things that surprised you? e) Were there things that you did not understand? f) How does the knowledge that you currently know differ from the knowledge that you used to think? [see Appendix B]).
Figure 3.1: Dissolving of a salt (Available at http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/ thermochem/solutionSalt.html).
Solid
Liquid
Gas
Figure 3.2: Motion of particles in three states of matter (Available at http://www.chem.purdue.edu/gchelp/atoms/states.html). 89
Unlike the RBTw/MR, the instructional component of the RBT did not include the Multiple Representations dimension. Students who followed the RBT instruction were engaged in the same activities as were the RBTw/MR group students (see Appendix A), but the instructional practices for the RBT group were slightly different compared to the instructional practices for the RBTw/MR group. For example, the teacher introduced the RBT group students to the static particle models of matter one time during the intervention, and the students in the RBT group were never asked to draw particle models for each given phenomenon. Instead, during the class presentations, students in the RBT group were asked to be more descriptive in their verbal explanations of the phenomena. Students in the RBT group were also provided activity sheets. The activity sheets for the RBT group were the same as the activity sheets for the RBTw/MR group, but they excluded the static particle models for three states of matter by keeping the textual background information as it was in the RBTw/MR group activity sheets. Moreover, the RBT group did not view the online animations that were made available to the RBTw/MR group students for the three macroscopically observed phenomena. The RBT group students were also asked to write down a one-page hand-written journal following each activity by answering the same prompts as those given to the RBTw/MR students. Regarding the suggestions offered by the past literature pertaining to the curriculum design (Vosniadou, Ioannides, Dimitrakopoulou, & Papademetriou, 2001), both the RBTw/MR and the RBT also recognized the significant role of students’ alternative conceptions in student learning. Accordingly, the content component of the both interventions was framed by extracting students’ alternative conceptions associated with the key aspects of the PNM from the past literature of science education. Moreover, 90
the physical science content standards in the reform initiatives (NRC, 1996; AAAS, 1993) were carefully examined to identify the specific Standards and the Benchmarks that correspond to those of students’ alternative conceptions of the PNM. The following learning goals, then, were established to address students’ frequently observed alternative conceptions of the PNM. Both groups of students were expected to understand that • • • • •
all matter is made up of particles. the particles in three states of matter are in continuous motion. the relative spacing between and arrangement of the particles in three states of matter are different. there is empty space between the particles of matter. there are attraction forces between the particles of matter, and the strength of these forces determine the physical state of matter. Table 3.2 describes the activities along with the types of instructional practices
used in the groups of the RBTw/MR and the RBT in facilitating student learning of intended learning goals as stated above (also see Appendix A and Appendix B).
Activities
Teaching for the RBTw/MR group
Teaching for the RBTw/MR group
Activity 1 Classifying matter.
Group work Whole-class discussion
Group work Whole-class discussion
Activity 2a Observing a solid air freshener as its vents are opened, and then, closed.
Group work Group-work Whole-class discussion Whole-class discussion Multiple representations • Observing a phenomenon • Observing a phenomenon. • Explaining the • Drawing two pictorial phenomenon at the particle particle models. level both orally and in written form. • Explaining the phenomenon Journal writing at the particle level both orally and in written form. Journal writing
Continued. Table 3.2: The instructional strategies implemented in RBTw/MR and RBT groups. 91
Table 3.2 continued.
Activities
Teaching for the RBTw/MR group
Teaching for the RBTw/MR group
Activity 2b Observing dissolution of potassium permanganate crystals in water with no stirring.
Group work Whole-class discussion Multiple representations • Observing a phenomenon. • Drawing two pictorial particle models. • Explaining the phenomenon at the particle level both orally and in written form. • Viewing online simulation of dissolving of a solid. Journal writing
Group-work Whole-class discussion • Observing a phenomenon • Explaining the phenomenon at the particle level both orally and in written form. Journal writing
Activity 2c Predicting and explaining the volume decrease when water and alcohol are mixed.
Group work Whole-class discussion • Explaining the phenomenon at the particle level both orally and in written form • The use of analogy Journal writing
Group work Whole-class discussion • Explaining the phenomenon at the particle level both orally and in written form • The use of analogy Journal writing
Activity 3 Part 1: Observing uniform distribution of food coloring in water without stirring.
Group work Whole-class discussion Multiple representations • Observing a phenomenon. • Drawing pictorial particle models. • Explaining the phenomena at the particle level both orally and in written form. • Viewing online simulation of motion of particles in three states of matter and diffusion of perfume particles in air. Journal writing
Group-work Whole-class discussion • Observing a phenomenon. • Explaining the phenomena at the particle level both orally and in written form. Journal writing
Part 2: Exploring the motion of solid particles with increasing temperature. Part 3: Observing the diffusion of perfume particles in air.
Continued.
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Table 3.2 continued.
Activities
Teaching for the RBTw/MR group
Teaching for the RBTw/MR group
Activity 4 Observing the compression of three syringes that are halffilled with air, water and sand respectively
Group work Whole-class discussion Multiple representations • Observing a phenomenon. • Drawing pictorial particle models. • Explaining the phenomena at the particle level both orally and in written form. Journal writing
Group-work Whole-class discussion • Observing a phenomenon. • Explaining the phenomena at the particle level both orally and in written form. Journal writing
Activity 5 Part 1: Observing melting of various solids such as ice, butter, candle wax, table salt, menthol, vanillin. Part 2: Observing evaporation of the stripes of water and alcohol on the chalkboard.
Group work Whole-class discussion Multiple representations • Observing a phenomenon. • Drawing pictorial particle models. • Explaining the phenomena at the particle level both orally and in written form. Journal writing
Group-work Whole-class discussion • Observing a phenomenon. • Explaining the phenomena at the particle level both orally and in written form. Journal writing
Data Collection and Recording Procedures The data were collected from September 2005 through February 2006. The researcher was present in both classes for about nine-weeks. The interventions were implemented in October/November 2005, and the instruction took 2.5 weeks (twelve class periods). After completion of the interventions, the researcher was in the school to administer a posttest to both groups of participants and to interview selected students from both groups. The first week of the February 2006 (three-months after the posttest), the researcher revisited these two classes to administer the delayed posttest.
93
Although the current study was rooted in the fundamentals of the quasiexperimental design, both qualitative and quantitative methods were integrated into the research methodology (Tashakkori & Teddlie, 1998). Aggregating multiple methods contributed to the purposes of complementarity, which permitted the examination of diverse facets of the students’ conceptions of the PNM when they engaged in the RBT and the RBTw/MR instruction, and expansion, which added the breath and scope to the current study (Greene, Caracelli, & Graham, 1989; Tashakkori & Teddlie, 1998). A variety of qualitative data collection methods were employed to search for evidence to answer the research questions. The data sources included open-ended questionnaires, student interviews, student artifacts, field notes, and videotapes of classroom conversations. The research questions were addressed by delineating the primary data sources, which were open-ended questionnaires and student interviews. The major part of the data analysis was descriptive and interpretive due to the nature of the way that the research questions were formulated. The statistical data analysis was performed to quantitatively assess the effectiveness of the RBTw/MR and RBT instruction in terms of change in and durability of students’ understanding of the PNM. The sections below describe each data source.
Open-ended Questionnaire This instrument, named the Nature of Matter–Diagnostic Questions (NMDQ), mainly originated from the questionnaire items used in previous research (Williamson, 1992). All original items utilized from previous research were reformulated with regard to the purposes of the current research, and totally new questions were added as well. The 94
NMDQ consisted of ten open-ended questions. The content of the NMDQ was aligned with the identified learning goals. Each learning goal was assessed at least twice in different contexts to ensure that students’ understanding of the key aspects of the PNM was not confined to the context (Jimenez Gomez, Benarroch, & Marin, 2006). To minimize the threats to internal validity of the quasi-experimental design (Best & Kahn, 1993; Campbell & Stanley, 1963), two forms of the NMDQ were created for the pre and the posttest. In order to not sensitize students’ attention to the pictorial particle model drawings, the pictorial particle model drawings were intentionally excluded from the pretest form of the NMDQ, with the exception of question 1. Thus, questions in the pretest form of the NMDQ were rewritten in a slightly different way while retaining the same context and content. In the posttest form of the NMDQ, most questions assessed students’ understanding of the key concepts of the PNM through pictorial particle model drawings along with open-ended questions that sought explanation for their drawings. A pilot test was conducted to identify if each question in the NMDQ yielded the likely responses and met the objectives of the current study. The content validity of the questionnaire was established by a panel of experts, including a science education professor who had specialized training and experience in chemistry, a chemistry lecturer with a doctoral degree in chemistry, and a doctoral candidate in chemistry. Considering students’ responses on the pilot test and the recommendations offered by the panel of experts, some of the items in two forms of the NMDQ were reworded to probe students’ understanding of the PNM more in depth. The two forms of the entire NMDQ are available in Appendix C.
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The participants took the pretest form of the NMDQ about two weeks before starting the implementation of the instructional interventions. The purpose of administering the pretest was to identify students’ preexisting understandings about the aspects of the PNM. The posttest form of the NMDQ was administered twice: first, one week after completion of the instructional interventions to assess the change in students’ understanding of the key aspects of the PNM; and second, three-months after administering the posttest to examine to what extent students in both groups retained what they learned about the PNM during the instructional interventions.
Student Interviews According to Patton (2002), the purpose of interviewing is “to find out what is in and on someone else’s mind” (p.341). Thus, a subset of students was interviewed, after they took the posttest, to better understand their way of thinking and to confirm their responses on the posttest (Jimenez Gomez et al., 2006). In the interviews, students were asked the same questions as on the posttest, and when needed, students’ ideas were probed in greater depth to gain more insight into the reasoning behind their responses and to clarify any vague responses they offered on the posttest. In a broad sense, the questions included “What do you mean by saying this? Could you please explain this a bit more? What does your drawing represent? Why do you think that happens in this case?” Nine students from the RBTw/MR group and six students from the RBT group were purposefully selected (Patton, 2002) based on their responses on the posttest. Students whose responses exhibited alternative conceptions of the PNM were particularly invited to the interviews to make sense of their way of viewing the given phenomena. 96
The selected students were interviewed individually. Interviews with each student took about twenty-five minutes. Each interview session was audiotaped and transcribed.
Student Artifacts During the instructional intervention, the teacher provided activity sheets to both the RBTw/MR and the RBT group students (see Appendix B). Thus, students were able to record their observations and communicate their inferences and reasoning in written form when they engaged in the intervention activities. These activity sheets also consisted of questions that probed students’ thinking more in depth while they observed the phenomenon at hand. Students in both groups first predicted what would happen, then, observed the given phenomenon, and then explained what happened at the particle level while they were observing. In addition to these procedures, the RBTw/MR group students generated particle models to visually represent the phenomenon. The activity sheets prepared for the RBTw/MR group included the pictorial particle models for three states of matter with relevant background knowledge to assist students in generating the particle models for the phenomenon that they observed. Unlike the activity sheets for the RBTw/MR group, the activity sheets for the RBT group excluded the particle models for three states of matter, but kept relevant background information the same as in the activity sheets for the RBTw/MR group. Moreover, the RBT group students neither were asked to sketch the pictorial particle models for the phenomena that they observed nor spontaneously drew the pictorial representations of the observed phenomena, instead they were asked to explain the phenomena in a detailed manner using particle ideas. Students
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in both groups were asked to turn in the activity sheets at the end of the each activity. Copies of the completed activity sheets were made to be used as additional data sources. After completion of each activity, students in both the RBTw/MR and the RBT groups were asked to write journal entries in order for the researcher to both gain insight into their classroom experiences and to identify the kinds of issues that made them confused and that they did not understand. Journal entries were hand written, no more than one-page in length, and included students’ reflections to the following prompts: What was this activity about? What do you know about the topic right now? Were there things that confused you? Were there things that surprised you? Were there things that you did not understand? How does the knowledge that you currently know differ from the knowledge that you used to think? Journal entries were a part of the instruction. Students in both groups were asked to write a total of six journals throughout the study. Each entry took about 10 minutes of the students’ time. Journal entries were collected and read as soon as they were handed in by students. Collecting and reading journal entries and student activity sheets served as formative assessment of student learning. Keeping track of each group of students’ progress while implementing the instructions provided great assistance to the researcher in terms of identifing the issues that students struggled with in learning the aspects of the PNM (Black & Wiliam, 1998a, 1998b). In cooperation with the teacher, those issues concerning student learning of the PNM were addressed in both classrooms. In this case, students’ pictorial and/or verbal representations were used as a resource for focusing their attention on particular concepts of the PNM. Students were asked for further clarification of their ideas/theories regarding the particulate actions of the observed phenomena. 98
Videotaped Classroom Conversations The conversations between the teacher-student and student-student in the wholeclass discussions were videotaped. The main purpose of videotaping was to describe the classroom context. Both the RBTw/MR and the RBT classrooms were videotaped on the days when the two types of instruction were carried out. In general, the focus of the videotape was the overall classroom, but in order to capture the teacher and students’ verbal statements, the focus was diverted to the teacher-student conversations when they were engaged in the whole-class discussions. If there were some instances that called for closer attention, the focus of the camera was turned to these events as well. The researcher made sure that the camera was positioned in such a way that students who did not participate in the study were not captured on the recording.
Field Notes The researcher also took field notes while videotaping each class. During videotaping, mental notes/keywords were recorded to help the researcher remember the events that occurred in the classroom. After each class period, the researcher worked on the mental notes to describe what happened in that class period with specific details including flow of activities performed in that class period, major interactions between students and the teacher, significant quotes (by referring to the videotape recording with time) that reflected students’ ways of understanding the concepts. Sometimes, the researcher added reflective thoughts to these notes to describe the things that did not occur as expected.
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Data Analysis Students’ written responses to the NMDQ were typed, and the figures that they drew as part of their responses were scanned to allow the researcher to be able to easily read, code, and organize the data. The interviews were transcribed entirely. Then, the electronic data were coded using both descriptive codes for qualitative analysis and the numeric values (scores) for quantitative analysis.
Qualitative Analysis The primary data sources, the written responses (both pictorial and verbal) to the NMDQ and the interview transcripts, were thoroughly analyzed by reading, rereading, and coding in order to identify the participants’ types of conceptual understandings of the PNM. Specifically, the procedures of the constant comparative method (Glaser, 1965; Glaser & Strauss, 1967; Trundle et al., In press) were employed in the data analysis. This method views the processes of data collection, coding, and analysis as a simultaneous and iterative. The codes that emerge from the data at the initial phase of the coding were divided into categories, (e.g., students’ scientific and alternative conceptions of the PNM), and the subsequent coding either verified these categories or modified them to fit the new data. New codes were included as they emerged from the data. In addition, the constant comparative method allowed for “joint coding and analysis” of the qualitative data (Glaser, 1965; p.437). In the final phase of the data analysis, “explicit coding and analytic procedures” permitted by the constant comparative method assisted the researcher in generating systematic holistic categories (Glaser & Strauss, 1967, p.102).
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Previous studies (Griffiths & Preston, 1992; Haidar & Abraham, 1991; Johnson, 1998c; Novick & Nussbaum, 1981; Sequeira & Leite, 1990; Williamson & Abraham, 1995) were used to establish a criteria for the scientific understanding and the probable alternative conceptions that participants might hold. The knowledge from the literature contributed to creating a “partial framework” (Glaser & Strauss, 1967, p.45) before beginning the data analysis. The partial framework and coding of some participants’ responses to the questionnaire on the pilot-test helped the researcher to design a coding sheet (see Figure 3.3) and the coding scheme (see Table 3.3) for the current study (Trundle, Atwood, & Christopher, 2002; Trundle et al., In press). The coding sheet facilitated the coding procedure and assisted the organization of the patterns that emerged from the data (Coffey & Atkinson, 1996). The final form of the coding sheet, which includes the concepts that each question assesses in the NMDQ, can be seen in Figure 3.3 (see p. 112). The initial form of the coding sheet was used as a guideline to begin coding students’ understanding of the key concepts of the PNM, but the coding process was not limited to the codes defined on an early form of the coding sheet. The new codes that emerged from the data were recorded on the coding sheet (see Figure 3.3, p. 112) and also added to the coding scheme along with the descriptions. The coding scheme was constantly modified with the addition of new codes as the data analysis continued (see Table 3.3, p.116). Data analysis started with coding participants’ verbal and pictorial responses to the ten questions on the pretest. In this coding process, the researcher looked for how participants’ verbal and pictorial responses lined up or did not line up with the coding scheme. As mentioned before, the coding scheme was not the strict criteria to judge 101
students’ understanding of the PNM. The coding scheme was reshaped as the new codes emerged from the data and until the scheme became stabilized. Then, codes were categorized and compared to the criteria established for the types of conceptual understandings (see Table 3.4, p.118). The categories of conceptual understandings were the collective reflection of the codes from the participants’ responses to the NMDQ on the pretest (Trundle et al., 2002; In press). For the data analysis of the posttest, the same coding sheet and scheme from the pretest were used. Participants’ verbal and pictorial responses to the NMDQ on the posttest were coded, and the new codes were recorded on the coding sheet and also integrated into the coding scheme. The same procedure was repeated for the interview data. Because “joint coding” is consistent with the constant comparative method, the codes from both sources were compared, and the joint codes were recorded on a blank coding sheet. Then, the codes that came from the coding of the responses to the NMDQ or the joint codes that were derived from the two data sources (NMDQ and interviews) were categorized and compared to the criteria for the types of conceptual understandings (see Table 3.4). Thus, each participant was assigned a type of understanding that collectively reflected the codes or the joint codes (Trundle et al., 2002, In press). Participants’ responses to the delayed posttest were coded using the same coding sheet and scheme used for the posttest data analysis. Participants’ verbal and pictorial responses to the NMDQ were coded, and the new codes were recorded on the coding sheet. The codes were then categorized and compared to the type of conceptual understanding criteria (see Table 3.4) to describe participants’ conceptual understandings of the PNM three-months after the instructional interventions of the RBT and RBTw/MR. 102
The types of conceptual understandings included scientific, scientific fragments, scientific with alternative fragments, alternative with scientific fragments, alternative fragments and no understanding (Trundle et al., 2002, In press) (see Table 3.4). A scientific understanding was defined as a conception in accord with the scientifically accepted eight key aspects of the PNM. If participants’ responses satisfied the most fundamental key aspect of the PNM, which was “matter is made up of particles,” and included a subset of the other seven accepted criteria for a scientific understanding without showing any alternative understanding, these participants’ conceptual understandings were categorized as scientific fragments. Alternative conceptions were described as “conceptions which are at variance with the scientifically acceptable conceptions” of the PNM (e.g., matter is continuous) (Hewson & Hewson, 1983, p.732). Participants’ conceptual understandings were categorized as scientific with alternative fragments if they exhibited a scientific understanding in four or more aspects of the PNM with at most three fragments of alternative conceptions. The type of understanding was identified as an alternative understanding with scientific fragments if the participants’ responses dominantly included a subset of alternative criteria with three or fewer scientific aspects of the PNM. If the participants’ responses consistently indicated a subset of alternative conceptions about the different aspects of the PNM with no evidence of exhibiting a scientific understanding in any aspect of the PNM, the type of understanding was identified as alternative fragments. Participants who did not display any type of understanding (scientific or alternative) in any aspect of the PNM were judged as having no conceptual understanding of the PNM.
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After coding and categorizing the participants’ responses on the pre, post, and delayed posttest, comparisons were made across participants to determine the patterns in the categorizations of conceptual understandings before, after, and three-months after instruction to identify the change in participants’ conceptual understandings of the PNM and the durability of conceptual understandings of the PNM over time. Then, the categories of conceptual understandings for participants in each group were compared across the three data collection points to identify the conceptual pathways (Scott, 1992) that individual students pursued from the beginning to the end of the study. In the current study, conceptual pathways demonstrated individual students’ learning routes that that they experienced from the pretest to the post to the delayed posttest (Scott, 1992). In the final phase of data analysis, students’ conceptions of each constituent aspect of the PNM for the three states of matter were classified as scientific, alternative, or no understanding. Then, the frequency count was performed for each group to identify how students’ conceptions of each aspect of the PNM varied from the pretest to the post to the delayed posttest. Trustworthiness of the Study According to Lincoln and Guba (1985), establishing the trustworthiness of the qualitative data is an important issue to convince the reader that the findings of the study are credible. Thus, the following strategies were utilized to enhance the trustworthiness of the qualitative data: member checking, prolonged engagement, and inter-rater reliability. Descriptions of how each strategy used in this study follow.
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Member Checking Member checking was used to confirm and further examine students’ conceptual understandings of the PNM. Students who gave inconsistent or vague responses on the posttest were interviewed to elucidate their responses on the test and check with them if the researchers’ interpretation of their responses was in parallel with what they really meant on the test. Prolonged Engagement To establish a prolonged engagement, the researcher started observing both groups five weeks before the instructional interventions began. In this five-week period, the researcher was able to get accustomed to the research site, gaining familiarity with the students and the classroom context. During a 2.5 week period when the instructional interventions were implemented, the researcher attended both sessions every day to videotape the classroom conversations, take field notes, and to observe the participants as they engaged in the activities. Inter-rater Reliability Twenty five percent of the students’ responses to the NMDQ on the pre, post, and the delayed posttest and the interview transcripts (for students who were interviewed) were randomly selected. The researcher and a graduate student who was trained how to code the data using the coding sheet designed for the current project each independently coded the selected data. The agreement for students’ types of conceptual understandings of the PNM was calculated at 90%. Krippendorff (2004) acknowledged percent agreement to be “a liberal index” and suggested using more conservative inter rater reliability indexes such as Cohen’s Kappa or Scott’s pi. The major weakness associated 105
with percent agreement is “its failure to account for agreement that would occur simply by chance” (Lombard, Snyder-Duch, & Champanella-Bracken, 2002, p.590). Hence, Cohen’s Kappa was found to be acceptable (κ = 0.85).
Quantitative Analysis Relying on the perspective in science education literature that considers knowledge as concept-like micro pieces [“a convenient unit of thought” (Minstrell, 1992, p.112)] within individuals’ knowledge framework (diSessa, 1988; Minstrell, 1992; Niedderer & Schecker, 1992), students’ responses to each item in the NMDQ on the pre, post, and the delayed posttest were divided into conceptual units. A coding sheet was developed to record the numeric points for each unit (see Table 3.5, p.120). While assigning a numeric score to each unit, students’ responses were compared to the scientifically accepted responses established by a panel of experts (see Appendix C). The same panel of experts who established the content validity of the NMDQ questionnaire provided responses for each questionnaire item. Their responses set the expert baseline for scientific responses of the NMDQ questionnaire. The numeric point of one (1) was assigned to each unit if students’ response was scientifically accurate and the point of zero (0) to all nonscientific responses. However, relative weights of the individual items varied item to item with regard to the number of conceptual units that existed within each item. For example, questionnaire item 1 assessed students’ perceptions of the discontinuity of matter in three states of matter so that students’ conception of the discontinuity of matter for each physical state was regarded as one conceptual unit with a total of three units, one for each state of matter. 106
Then, the relative weight of 3 was allotted for question number 1. On the pretest, relative weights of items ranged from one to three points and added up to the highest likely total score of 22. On the post and the delayed posttest, relative weights of items varied between one and six points, and added up to the highest likely total score of 34. Ten percent of the students’ responses to the NMDQ on the pre, post, and the delayed posttest were independently scored by the researcher and a graduate student who is familiar with the content of the questionnaire. The Spearman rank-order correlation coefficient was computed to determine the consistency of rankings for the total scores obtained for each student by the two raters. The ranked total score values of the two raters was a strong (Spearman’s Rho) rank-order correlation of rs = = 0.864, p = 0.000. Nonparametric statistics were conducted to analyze the numeric data obtained in this study (Siegel & Castellan, 1988). The Wilcoxon-Mann-Whitney test was selected for evaluating both the conceptual similarity of the two groups prior to the interventions in terms of understanding the key aspects of the PNM and the conceptual change in/the durability of students’ understanding of the PNM due to the impact of the instructional interventions of the RBT and the RBTw/MR. The assumptions for the Wilcoxon-MannWhitney test were met with the use of two independent samples and ordinal data. The Wilcoxon-Mann-Whitney test was run using the pretest scores to ensure that the two groups before the intervention held the similar conceptual understandings of the PNM. The same test was employed to identify if there was a statistically significant difference between two groups of students’ conceptual understandings of the PNM immediately after completion of the instructional interventions of the RBTw/MR and the RBT. The exact same procedures were repeated to determine if there was a significant difference 107
between the RBTw/MR and the RBT group students in terms of maintaining the scientific conceptions constructed during instruction. The following null hypotheses were tested by using Wilcoxon-Mann-Whitney procedures: 1. There is no median difference between the two groups of students on their preNMDQ scores in terms of understanding the aspects of the PNM, before they participated in any type of instruction. H0 = MRBTw/MR (pre) – MRBT (pre) = 0 2. There is no median difference between the students who participated in the RBTw/MR and those completed the RBT on their post-NMDQ scores in terms of understanding the aspects of the PNM. H0 = MRBTw/MR (post) – MRBT (post) = 0 3. There is no median difference between the students who participated in the RBTw/MR and those completed the RBT on their delayed-NMDQ scores in terms of understanding the aspects of the PNM. H0 = MRBTw/MR (delayed) – MRBT (delayed) = 0 Research question number 3 was developed to determine if there was any statistically significant difference within each group in terms of students’ understandings of the PNM just after and three-months after completion of the interventions of the RBT and the RBTw/MR. The Sign test was chosen to address this particular question. To run the test, students’ types of conceptual understandings that were identified in the qualitative analysis were quantified as zero (0) for no conceptual understanding, one (1) for alternative fragments, two (2) for alternative with scientific fragments, three (3) for scientific with alternative fragments, four (4) for scientific fragments and five (5) for 108
scientific understanding. These numerical values were assigned for the types of conceptual understandings exhibited by the participants on the pre, post, and the delayed posttest. The assumptions for the Sign test were satisfied with having one variable, one sample, and independent observations. The following null hypotheses were tested for each group. 1. There is no median difference between the types of understandings students held before and after the instructional interventions of the RBT and the RBTw/MR. H0: Mpre = Mpost. 2. There is no median difference between the types of understandings students held before and three-months after the instructional interventions of the RBT and the RBTw/MR. H0: Mpre = Mdelayed-post. Validity Issues of the Quasi-Experimental Study This study is similar to a controlled experimental design, except that the students were not randomly assigned to either the RBTw/MR or the RBT group. However, individual groups were randomly chosen for instructional interventions of the RBTw/MR and the RBT. To attribute observed differences between the two groups of students due to instruction, possible threats to internal validity of quasi-experimental design needed to be minimized (Cook & Campbell, 1979). The following section describes the ways in which some specific threats to internal validity were controlled in the current study. Selection Selection could be a threat due to the nonequivalence of the two groups (Cook & Campbell, 1979). Although students were not randomly assigned to the two groups in the 109
current study, the Wilcoxon-Mann-Whitney test performed on students’ pretest scores confirmed that statistically, there was no significant difference between the RBTw/MR and the RBT group students’ conceptual understandings of the PNM (see Chapter 4). History History can be “a threat when an observed effect might be due to an event which takes place between the pretest and the posttest” (Cook & Campbell, 1979, p.51) such as natural disasters, the anxiety generated by pending examination (Best & Kahn, 1993). In this study, the tests (the pre, post, and the delayed posttest) were applied on the same days in both groups, and no external events that might influence the students’ performance on the test were evidenced. Maturation Participants change over a period of time in many ways, and the change observed in their biological and psychological functioning of the body may interfere with the independent variable (students’ conceptual understandings) under investigation (Best & Kahn, 1993; Cook & Campbell, 1979). For example, students may become older, wiser, more experienced from the pre to the posttest. In the current study, all participants, except one student from the RBT group (twelfth grade), were enrolled in the eleventh grade. An eight-week period can be considered to be a relatively long time to establish a prolonged engagement with the participants, but regarding the fact that students took the posttest five weeks after taking the pretest, maturation had no or little threat between the pre and the posttest. On the other hand, three months elapsed between the post and the delayed posttest. This amount of time does not seem to be a considerable threat to the inter
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validity either, because the same teacher continued to teach the classes so that students in both groups had similar learning experiences in this period of time. Mortality Mortality refers to the loss of participants, and this might be a threat, because an effect recorded between groups might be attributed to the students who dropped out of the study during the course of the study (Cook & Campbell, 1979). However, in the current study, none of the tests were announced before the test day. Thus, students’ absences on the test day were due to other reasons. A total of five students were dropped out of the study for various reasons such as missing data. Instrumentation and Testing Pretesting may create a practice effect so that participants may perform better due to acquired proficiency on the pretest (Best & Kahn, 1993). In this study, the threat to the internal validity due to testing and instrumentation was reduced by having an equivalent instructional group and administering different forms of the questionnaire on the pre and the posttest. The researcher prepared two forms of the questionnaire (NMDQ). The posttest form of the questionnaire included particle model drawing sections for almost all questions, but these sections were purposely excluded from the pretest form of the questionnaire to not induce students’ attention to the drawings during the instructional intervention. Moreover, on the delayed posttest, students took the exact same test as on the posttest, but the duration of time between the post and the delayed posttest was three months. Therefore, the length of the time was notably longer to lessen students’ familiarity with the questions.
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Student: …………………………………............................... Pre
Post
Delayed
Types of Conceptual Understandings Scientific Scientific Scientific with Alternative Understanding Understanding Fragments Alternative Fragments with Scientific Fragments
Alternative Understanding
No Understanding
1) Question 1 assesses students’ ability to recognize that “matter is not continuous, but made up of particles” with no given prompt of particle ideas. In other words, this primarily assesses students’ visualization of matter in three physical states. Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Alt_ Alt_ Alt_ Alt_ Alt_ Part Arr Dist Move Force Empty Uni Dns Part Arr Dist Move Force
Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Empty Uni Dns Color Bond Size Diss
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Solid Liq. Gas
2) Question 2 assesses students’ ability to recognize that particles of a gas are uniformly distributed and the density of gases changes when half of the gas is released from the closed container. Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Part Arr Dist Move Force Empty Uni Dns Part Arr Dist Move Force Empty Uni Dns Color Bond Size Diss Solid Liq. Gas
Continued. Figure 3.3: Coding Sheet 1. 116
Figure 3.3 continued. 3) Question 3 probes students’ ability to recognize the differences between the three states of matter in terms of the arrangement of and of the relative spacing between the particles. Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Alt_ Alt_ Alt_ Alt_ Alt_ Part Arr Dist Move Force Empty Uni Dns Part Arr Dist Move Force
Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Empty Uni Dns Color Bond Size Diss
Solid Liq. Gas
4) Question 4 assesses students’ ability to understand that water particles play the key role in dissolving of a solid due to their (water particles) ability to move, and that particles of a solid are uniformly distributed in a liquid when a solid dissolves. Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Alt_ Alt_ Alt_ Alt_ Alt_ Part Arr Dist Move Force Empty Uni Dns Part Arr Dist Move Force
Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Empty Uni Dns Color Bond Size Diss
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Solid Liq. Gas
5) Question 5 assesses students’ understanding of the movement and the uniform distribution of liquid molecules in another liquid. The molecules of food coloring diffuse through water from an area of high concentration to an area of low concentration due to their ability to move. Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Alt_ Alt_ Alt_ Alt_ Alt_ Part Arr Dist Move Force Empty Uni Dns Part Arr Dist Move Force
Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Empty Uni Dns Color Bond Size Diss
Solid Liq. Gas
Continued. 117
Figure 3.3 continued. 6) Question 6 assesses students’ understanding of the uniform distribution of gases due to random movement of the gas particles. Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Alt_ Alt_ Alt_ Alt_ Alt_ Part Arr Dist Move Force Empty Uni Dns Part Arr Dist Move Force
Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Empty Uni Dns Color Bond Size Diss
Solid Liq. Gas
7) Question 7 probes students’ ability to identify the possible differences that occur during the phase changes in the arrangement of, the distances between (change in density) and the motion of particles. 114
Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Alt_ Alt_ Alt_ Alt_ Alt_ Part Arr Dist Move Force Empty Uni Dns Part Arr Dist Move Force
Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Empty Uni Dns Color Bond Size Diss
Solid Liq. Gas
8) Question 8 tests students’ ability to link the changes in the arrangement of, the relative spacing between and the motion of solid particles during the phase changes due to the change in the strength of the forces that act between particles. Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Alt_ Alt_ Alt_ Alt_ Alt_ Part Arr Dist Move Force Empty Uni Dns Part Arr Dist Move Force
Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Empty Uni Dns Color Bond Size Diss
Solid Liq. Gas
Continued. 118
Figure 3.3 continued. 9) Question 9 probes students’ ability to recognize the change in the distances (density) between particles of gases when the volume that the gas occupies changes. The change in distances can occur due to the large empty space among particles of gases. Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Alt_ Alt_ Alt_ Alt_ Alt_ Part Arr Dist Move Force Empty Uni Dns Part Arr Dist Move Force
Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Empty Uni Dns Color Bond Size Diss
Solid Liq. Gas
10) Question 10 assesses students’ knowledge of the notion of a vacuum that exist between the particles of matter. 115
Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Sci_ Alt_ Alt_ Alt_ Alt_ Alt_ Part Arr Dist Move Force Empty Uni Dns Part Arr Dist Move Force Solid Liq. Gas
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Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Alt_ Empty Uni Dns Color Bond Size Diss
Code
Meaning of Code
SciPart
Matter is made up of particles.
SciArr
Particles of matter are differently arranged in the three states of matter. (Particles of solids are arranged in symmetric arrays. Particles of liquids and gases are arranged randomly.)
SciDist
There are large distances between the particles of gases, but the particles of solids and liquids are closely packed and the distances between the particles of solids and liquids are similar.
SciMove
Particles of solids vibrate at a fixed point; liquid particles have flexibility of movement, and gas particles freely move.
SciForce
There are strong attraction forces between the particles of a solid. These forces weaken as a solid turns into a liquid, then, a gas.
SciEmpty
Nothing exists between the particles of matter.
SciUni
Particles of a gas are uniformly distributed even if half of the gas is released. Particles of a liquid uniformly mix with particles of another liquid if the two liquids are miscible. Particles of a solid are uniformly distributed in water when a solid dissolves.
SciDns
The density of gas particles changes if a gas is added or released from the closed container. The density of matter changes when it undergoes a phase change such as melting or condensation.
AltPart
Matter is continuous.
AltArr
Particles of a solid are randomly arranged. Particles of a liquid are regularly arranged. The relative spacing among particles of a liquid is considered as in between the distances among particles of a solid and a gas.
AltDist AltMove
The particles of a solid either do not move or move very fast. Continued.
Table 3.3: Meaning of the codes.
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Table 3.3 continued.
Code
Meaning of Code
AltForce
The intermolecular forces are considered as intramolecular (chemical bonds). Or, physical changes are considered to be a chemical change, such as dissolving and mixing of two liquids or two gases.
AltEmpty
Air or some other material(s) exists between particles of matter. OR Students’ drawings show this phenomenon in such a way that particles are embedded in other substance.
AltUni
Gas particles are not uniformly distributed, when half of the gas is pumped out. Particles of a solid or liquid are accumulated at one spot in another liquid even after dissolving or mixing occurs.
AltDns
The density of a gas does not change when it turns into a liquid or when it is compressed without releasing any gas from the syringe.
AltColor
Particles of colorless substance such as water (or air) become colored by a colored substance such as food coloring (or colored gas).
AltBond
The solid lines (bonds) exist between particles to show that particles are close together.
AltSize
Size of the particles increase as the gas turns into a liquid then a solid.
AltDiss
Water absorbs the sugar molecules when sugar dissolves in water OR sugar melts when it is put into water.
NoCU
Not enough evidence to code the response.
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Type of Understandings
Criteria
Scientific Understanding
Must include all of the following scientific conceptual understanding criteria: • Matter is NOT continuous, but made of tiny particles. • Particles of solids, liquids and gases are in constant motion. • There are forces that act between the particles. • Particles of solids, liquids and gases are arranged differently. • Particles of solids and liquids are spaced similarly, but there are large distances between the particles of gases. • Particles of gases are uniformly distributed. Particles of solids and liquids are uniformly distributed when they dissolve or mix. • The density of gas particles changes if a gas is added or released from the closed container. The density of matter changes when it undergoes a phase change such as melting or condensation. • A vacuum (empty space) exists between the particles of matter.
Scientific Fragments
Must include scientific criteria of “Matter is made up of tiny particles” and includes a subset of the other seven scientific criteria, but not all of them.
Scientific with Alternative Fragments
Must include scientific criteria of “Matter is made up of tiny particles” at least in two states of matter, and includes a subset of the other seven aspects of the PNM with at most three alternative criteria (see Alternative Fragments).
Alternative with scientific fragments
Include a subset of the alternative criteria indicated in alternative fragments section with two scientific aspects of the PNM. Continued.
Table 3.4: Types of Conceptual Understandings and Criteria.
118
Table 3.4 continued.
Type of Understandings Alternative Fragments
No Understanding
Criteria Include a subset of conceptual understandings that are in conflict with scientific aspects of the PNM with no fragments of scientific understanding. The alternative conceptions emerged from the data: • Matter is continuous. • Particles of a liquid float in something else, which means that particles of a liquid and liquid itself are considered to be different. • The particles of a solid either do not move or move very fast. • When two liquids or two gases mix, the particles are bonded OR a new substance forms. • Particles of a solid are randomly arranged. • Solid lines exist between particles of a solid and/or a liquid to show that they are connected one another. • Particles of a liquid are regularly arranged with solid lines between particles. • Particles of a liquid are not closely packed as much as particles of a solid. • Particles of a gas accumulate either at the top or the bottom of the container when half of the gas is released from the container. • Two gases do not mix uniformly considering that two gases have the same density. • Particles of colorless substance such as water (or air) are dyed by colored substance such as food coloring (or colored gas). • When an amount of a gas turns into a liquid, the gas becomes heavy. • Air or other materials exist(s) between particles of matter. • Water absorbs the sugar molecules when sugar dissolves in water OR sugar melts when it is put into water. • Size of the particles increase as the gas turns into a liquid, then, a solid. There is no or enough evidence to judge students’ understanding as scientific or alternative understanding of the PNM.
119
Student:……………………………………………………………………………….
Pretest Question
Explain
Posttest Drawing
Explain
Delayed Posttest Drawing
Explain
Part_S
Part_S
Part_S
Part_L Part_G
Part_L Part_G
Part_L Part_G
Uni_G
Uni_G
Uni_G
Dense_G
Dense_G
Arr-Dist_G
Arr-Dist_G
Arr-Dist_G
Dense_G ArrDist_G
Arr-Dist_G
Arr-Dist_L
Arr-Dist_L
Arr-Dist_L
Arr-Dist_L
Arr-Dist_L
Arr-Dist_S
Arr-Dist_S
Arr-Dist_S
Arr-Dist_S
Arr-Dist_S
Move_S
Arr-Dist_S
Move_S
Arr-Dist_S
Move_S
Move_L Uni_aq
Arr-Dist_L Uni_aq
Move_L
Arr-Dist_L Uni_aq
Move_L
5
Move_L Uni_L
Arr-Dist_L Uni_L
Move_L Uni_L
Move_L Uni_L
6
Move_G
Arr-Dist_G
Move_G
Arr-Dist_L Uni_L ArrDist_G
Uni_G
Uni_G
Uni_G
Uni_G
Uni_G
Move_G
Dense_L
Move_G
Dense_L
Move_G
1
2
3
4
7 8
Dense_L Move_S
Dense_L ArrDist_L
Force_S
9
Dist_G Empty_G
10
Empty_G
Total
Force_S
Dense_L ArrDist_L
Move_S Dense_G
Dist_G Empty_G
Total
Pretest
Posttest
Total
Dense_G
120
Dist_G Empty_G Empty_G
Total Delayed
Table 3.5: Coding Sheet 2.
Force_S Move_S
Empty_G
Total
Move_G
Total
CHAPTER 4 ANALYSIS OF DATA Introduction The data analysis of this mixed-method study consisted of two distinct parts, the qualitative and the quantitative components, which were utilized to address the guiding research questions for the present inquiry. The findings were organized around the research questions and presented in four broad sections. The first section describes the RBTw/MR group students’ types of conceptual understandings of the PNM before, immediately after, and three-months after the instruction, including the unique conceptual pathways pursued by individual students from the pretest to the post to the delayed posttest. The second section is organized in the same way as the first section in order to articulate the RBT group students’ types conceptual understandings of the PNM before, immediately after, and three-months after the instruction in tandem with the portrayal of the conceptual pathways that individual RBT group students accomplished from the pretest to the post to the delayed posttest. The third section compares the RBTw/MR and RBT group students’ conceptual understandings of the PNM within and across the groups with regard to descriptive and statistical analysis. The fourth section discusses the prevailing patterns identified in each group of students' types of conceptions in relation to the conceptual components of the PNM across three data collection points. 121
The RBTw/MR Group Students’ Conceptual Understandings of the PNM
Types of Conceptual Understanding Categories Six types of conceptual understanding categories were established for the current study, namely, from scientific to nonscientific—scientific understanding, scientific fragments, scientific understanding with alternative fragments, alternative understanding with scientific fragments, alternative fragments and no understanding. Consistency in students’ pictorial representations and verbal explanations across different contexts on each test and in interviews were taken into consideration in identification of their types of conceptual understandings. The criteria for each type of conceptual understanding and the meaning of the codes presented in alternative conceptions column in tables below (e.g., Table 4.1) were fully explained in Chapter 3 (see Table 3.3, p. 116 and Table 3.4, p. 118).
Before the RBTw/MR Intervention Question 1a.1: What are the types of conceptual understandings held by high school students about the aspects of the PNM just before starting the RBTw/MR instruction? Before the students’ engagement in the instructional intervention called ReformBased Teaching with Multiple Representations (RBTw/MR), all students in this group held a range of alternative conceptions of the PNM and the conceptions occurred in various frequencies. That is, many of the RBTw/MR students exhibited an understanding of pieces of the particulate nature of matter, but all students in this group failed to create a connected whole picture of the PNM. Thus, none of the RBTw/MR students’ conceptual understandings were classified as scientific or scientific fragments before the instruction. 122
Regarding the six types of conceptual understanding categories, the RBTw/MR students’ understandings of the PNM before the instruction were considered to be less scientific or mostly nonscientific. Table 4.1 summarizes the RBTw/MR students’ types of conceptual understandings before the instruction with specific notes that indicate for which aspects of the PNM they held alternative conceptions and no conceptual understanding (NCU), including the data sources that were coded in identification of students’ type of conceptual understanding. To distinguish the two groups of students (RBTw/MR and RBT), the numbers assigned to the RBTw/MR students were combined with a letter “m” in reference to the instructional group that included multiple representations. For the RBT group, no letter is used with individual student numbers, which refers to the instructional group without multiple representations.
Participants
Type of Conceptual Understanding
Student # 1m
Scientific with Alt.Frag.
Pre-NMDQ
Arr_S; Dist_L; Move_S; NoCUof_Force & Uni_G
Student # 2m
Scientific with Alt. Frag.
Pre-NMDQ
Part_S; Dist_L, Empty_G; NoCUof_Force
Student # 3m
Alternative with Sci. Frag.
Pre-NMDQ
Dist_L, Force_S_L_G; Empty_G; NoCUof_Part &Arr_S_L & Move_S & Uni_G
Student # 4m
Alternative with Sci. Frag.
Pre-NMDQ
Arr_S; Dist_L; Empty_G; NoCUof_Part & Force & Move_S_G & Uni & Dense_S_L
Student # 5m
Alternative with Sci. Frag.
Pre-NMDQ
Student # 6m
Scientific with Alt. Frag.
Pre-NMDQ
Arr_S_G; Dist_G; Uni_G; Force_L_G; NoCUof Move S L G Arr_S, Dist_S_L
Data Sources
Alternative Conceptions
Continued. Table 4.1: Students’ types of conceptual understandings prior to the RBTw/MR. 123
Table 4.1 continued.
Participants
Type of Conceptual Understanding
Student # 7m
Alternative with Sci. Frag.
Pre-NMDQ
Student # 8m
Alternative with Sci. Frag.
Pre-NMDQ
Student # 9m
Alternative Fragments
Pre-NMDQ
Student # 10m
Alternative with Sci. Frag.
Pre-NMDQ
Student # 11m
Scientific with Alt. Frag.
Pre-NMDQ
Student # 12m
Alternative with Sci. Frag.
Pre-NMDQ
Arr_S; Dist_L; Force_S; Empty_G
Student # 13m
Alternative with Sci. Frag.
Pre-NMDQ
Arr_S; Dist_L; Uni_G; Empty_G
Student # 14m
Alternative with Sci. Frag.
Pre-NMDQ
Arr_S; Dist_L; Color; Empty_G; NoCUof_Force
Student # 15m
Alternative with Sci. Frag.
Pre-NMDQ
Student # 16m
Alternative with Sci. Frag.
Pre-NMDQ
Part_G; Arr_S; Dist_S_L; Uni_G; Empty_G; NoCUof_Force & Dense_L Arr_S; Dist_S_L; Force_S_L_G; Color; Empty_G; NoCUof_Move_S & Uni_L & Dense_L
Student # 17m
Alternative with Sci. Frag.
Pre-NMDQ
Arr_L; Dist_L; Move_S; Force_S_L; NoCUof_Dense_L
Student # 18m
No Understanding
Pre-NMDQ
Student # 19m
Alternative with Sci. Frag.
Pre-NMDQ
Student # 20m
Alternative with Sci. Frag.
Pre-NMDQ
Part_S_L_G; NoCUof_Arr & Dist & Move & Force & Empty & Uni & Dense_L_G Part_S_L_G; Move_S; NoCUof_Force & Uni_L & Arr_S_L_G & Dist_S_L_G Arr_S; Dist_S_L; Uni_G; Move_S; Empty_G; NoCUof_Force & Uni_L & Dense_L_G
Data Sources
Alternative Conceptions Part_S; Move_S; Uni_G; Empty_G, Force_L; NoCUof_ Arr_S_L & Force_S & Dense_L Part_L_G; Arr_S; Dist_S_G; Empty_G; NoCUof_Force & Dist_L & Dense_L_G Part_S_L_G; Dist_S_L_G; Uni_G; Empty_G; NoCUof_Arr_S_L_G & Force & Uni_L & Dense_L_G Arr_S_L; Dist_S; Force_S_G; Empty_G; NoCUof_Uni_L_G & Dense_L Dist_L; Force_L; NoCUof_Move_S & Dense_L
Continued. 124
Table 4.1 continued.
Participants
Type of Conceptual Understanding
Student # 21m
Data Sources
Alternative Conceptions
Alternative with Sci. Frag.
Pre-NMDQ
Part_L; Arr_S; Dist_S_L; NoCUof_Force & Empty_G
Student # 22m
Alternative with Sci. Frag.
Pre-NMDQ
Dist_L; Move_S; Force_S; Empty_G
Student # 23m
Alternative with Sci. Frag.
Pre-NMDQ
Dist_L; Force_G; Empty_G; Color; NoCUof_Uni_L
Pretest
Posttest
Delayed Posttest
Scientific
0 (0%)
11 (47.8%)
7 (30.4%)
Scientific fragments
0 (0%)
1 (4.3%)
1 (4.3%)
Scientific w/alternative frag.
4 (17.4%)
8 (34.8%)
10 (43.6%)
Alternative w/scientific frag.
17 (74%)
3 4 (13.1 %) (17.4%)
Alternative Frag.
1 (4.3%)
0 (0%)
1 (4.3%)
No Understanding
1 (4.3%)
0 (0%)
0 (0%)
Total
23 (100%)
23 (100%)
23 (100%)
Table 4.2: Summary of conceptual understandings for the RBTw/MR group.
Table 4.2 summarizes the frequencies of the types of conceptual understandings held by the RBTw/MR students. As shown in Table 4.2 below, only 4 of the 23 (17.4%) 125
RBTw/MR group students’ conceptual understandings were classified as scientific understanding with alternative fragments. These four students (numbers 1m, 2m, 6m and 11m) met several of the scientific criteria, but also held a few (at most three) alternative conceptions about the aspects of the PNM. A majority (74%) of the RBTw/MR students (numbers 3m, 4m, 5m, 7m, 8m, 10m, 12m, 13m, 14m, 15m, 16m, 17m, 19m, 20m, 21m, 22m, 23m) held alternative understandings with scientific fragments. These students showed alternative conceptions in more than three aspects of the PNM with one or two scientific fragments. One of the 23 (4.3%) RBTw/MR students (number 9m) had alternative fragments that included a subset of alternative conceptions with no evidence of understanding any scientific aspects of the PNM. One (number 18m) RBTw/MR student’s responses to the questionnaire tasks either included irrelevant answers or were left blank, so his conceptual understanding was categorized as no understanding.
After the RBTw/MR Intervention Question 1b.1: What are the types of conceptual understandings held by high school students about the aspects of the PNM just after completion of the RBTw/MR instruction? Although 82.6% of the RBTw/MR students’ conceptual understandings were classified as alternative with scientific fragments, alternative fragments or no understanding before they were involved in the instruction, almost all students (91.3%), after the instruction, progressed to the type of conceptual understanding that was at least one category advanced from their previous types of conceptual understandings. Categories of the types of conceptual understandings after the intervention are listed in 126
Table 4.3, including the data sources that were used in characterization of students’ types of conceptual understandings as well as the alternative conceptions or no conceptual understandings (NCU) that students held, if any. As presented in Table 4.3 below, 11 of the 23 (47.8%) RBTw/MR students were identified as holding a scientific understanding immediately after the instruction. These students (numbers 1m, 2m, 3m, 5m, 6m, 9m, 11m, 12m, 16m, 17m, 22m) consistently showed evidence of understanding all eight scientific criteria of the PNM. One (4.3%) of the RBTw/MR students’ (number 21m) explanations were scientific in many aspects of the PNM, but her failure to provide an explanation for all eight conceptual aspects of the PNM situated her conceptual understanding in the scientific fragments category. Eight of the 23 (34.8%) RBTw/MR students (number 4m, 7m, 8m, 13m, 14m, 15m, 20m, 23m) showed a scientific understanding with alternative fragments. Only 3 of the 23 (13.1%) RBTw/MR students (numbers 10m, 18m, 19m) held an alternative understanding with scientific fragments after their engagement in the instruction. No student’s conceptual understanding was classified as either alternative fragments or no understanding following the RBTw/MR instruction.
Participants
Type of Conceptual Understanding
Student # 1m
Scientific Understanding
Student # 2m
Scientific Understanding
Post-NMDQ & Interview Post-NMDQ
Student # 3m
Scientific Understanding
Post-NMDQ
Data Sources
Alternative Conceptions
Continued. Table 4.3: Students’ types of conceptual understandings shortly after the RBTw/MR. 127
Table 4.3 continued.
Participants
Type of Conceptual Understanding
Student # 4m
Scientific with Alt. Frag.
Student # 5m
Scientific Understanding
Post-NMDQ & Interview Post-NMDQ
Student # 6m
Scientific Understanding
Post-NMDQ
Student # 7m
Scientific with Alt. Frag.
Post-NMDQ
Arr_S_L; Dist_S; Size_S_L
Student # 8m
Scientific with Alt. Frag.
Post-NMDQ & Interview
Dist_L; Dense_L; Empty_G
Student # 9m
Scientific Understanding
Post-NMDQ & Interview
Student # 10m
Alternative with Sci. Frag.
Post-NMDQ
Student # 11m
Scientific Understanding
Student # 12m
Scientific Understanding
Post-NMDQ & Interview Post-NMDQ
Student # 13m
Scientific with Alt. Frag.
Post-NMDQ & Interview
Dist_L; Uni_G; Empty_S_L
Student # 14m
Scientific with Alt. Frag.
Post-NMDQ & Interview
Arr_L; Dist_S_L; Bond_S_L
Student # 15m
Scientific with Alt. Frag.
Post-NMDQ & Interview
Color; Empty_G; NoCUof_Force
Student # 16m
Scientific Understanding
Post-NMDQ
Student # 17m
Scientific Understanding
Post-NMDQ
Student # 18m
Alternative with Sci. Frag.
Post-NMDQ
Student # 19m
Alternative with Sci. Frag.
Post-NMDQ
Student # 20m
Scientific with Alt. Frag.
Post-NMDQ
Student # 21m
Scientific Fragments
Post-NMDQ
Student # 22m
Scientific Understanding
Post-NMDQ
Student # 23m
Scientific with Alt. Frag.
Post-NMDQ & Interview
Data Sources
128
Alternative Conceptions Dist_L; NoCUof_Force & Move_S
Arr_L; Dist_S_L_G; Bond_S_L; Color; Force_S
Arr_L_G; Dist_L; Uni_L_G; Dense_L; Empty_G; NoCUof_ Force Part_S; Arr__S_L_G; Dist_S_L_G; Dense_L_G; NoCUof_Force Arr_L; Dist_L; Empty_G; NoCUof Force NoCUof_Force
Dist_L
Three-Months after the RBTw/MR Intervention Question 1c.1: What are the types of conceptual understandings held by high school students about the aspects of the PNM three-months after completion of the RBTw/MR instruction? Categories of conceptual understandings three-months after the RBTw/MR instruction are presented in Table 4.4 and the types of alternative conceptions held by each student are specified. Three-months after the instruction, 78.3% (18 of 23) of the RBTw/MR students still held the scientific conceptual understandings such as scientific, scientific fragments or scientific with alternative fragments (see Table 4.2 above). In other words, a majority of the RBTw/MR students were still retaining much of what they learned about the aspects of the PNM on the delayed posttest. In a specific sense, 7 of the 23 (30.4%) RBTw/MR students (numbers 1m, 2m, 6m, 11m, 12m, 16m, 17m) were identified as scientific, 1 of the 23 (4.3%) students (number 22m) as scientific fragments and 10 of the 23 (43.6%) students (number 3m, 4m, 5m, 7m, 8m, 9m, 10m, 13m, 14m, 15m) as scientific with alternative fragments. Four of the 23 (17.4%) students (numbers 19m, 20m, 21m, 23m) exhibited alternative understanding with scientific fragments, and only one (4.3%) of the 23 students (number 18m) had alternative fragments.
Participants
Type of Conceptual Understanding
Data Sources
Student # 1m
Scientific Understanding
Delayed-NMDQ
Student # 2m
Scientific Understanding
Delayed-NMDQ
Alternative Conceptions
Continued. Table 4.4: Students’ types of conceptual understandings three-months after RBTw/MR. 129
Table 4.4 continued.
Participants
Type of Conceptual Understanding
Data Sources
Alternative Conceptions
Student # 3m
Scientific with Alt. Frag.
Delayed-NMDQ
Move_S
Student # 4m
Scientific with Alt. Frag.
Delayed-NMDQ
Arr_L; Dist_L; Uni_G; NoCUof_Force
Student # 5m
Scientific with Alt. Frag.
Delayed-NMDQ
Student # 6m
Scientific Understanding
Delayed-NMDQ
Uni_G_L; NoCUof_Force & Move S
Student # 7m
Scientific with Alt. Frag.
Delayed-NMDQ
Arr_S_L; SizeS_L; NoCUof_Force
Student # 8m
Scientific with Alt. Frag.
Delayed-NMDQ
Dist_L; Size_L_G; Dense_L; NoCUof_Force & Move_S
Student # 9m
Scientific with Alt. Frag.
Delayed-NMDQ
Dist_L
Student # 10m
Scientific with Alt. Frag.
Delayed-NMDQ
Student # 11m
Scientific Understanding
Delayed-NMDQ
Arr_L; Dist_L; Color; NoCUof Force
Student # 12m
Scientific Understanding
Delayed-NMDQ
Student # 13m
Scientific with Alt. Frag.
Delayed-NMDQ
Dist_L
Student # 14m
Scientific with Alt. Frag.
Delayed-NMDQ
Dist_L; Empty_L; Size_L_G
Student # 15m
Scientific with Alt. Frag.
Delayed-NMDQ
Student # 16m
Scientific Understanding
Delayed-NMDQ
Empty_L; Color; Uni_L; NoCUof Force
Student # 17m
Scientific Understanding
Delayed-NMDQ
Student # 18m
Alternative Understanding
Delayed-NMDQ
Part_S; Empty_G; Dense_L; NoCUof_Force_Arr_Dist_S_L_ G & Move_G & Uni_L
Student # 19m
Alternative with Sci. Frag.
Delayed-NMDQ
Part_S; Arr_L; Dist_L; Move_S NoCUof_Force & Dense_L
Student # 20m
Alternative with Sci. Frag.
Delayed-NMDQ
Arr_L; Dist_L; Uni_L_G; Empty_G; Dense_G; NoCUof_Force & Move_S_G
Student # 21m
Alternative with Sci. Frag.
Delayed-NMDQ
Dist_L; Dense_L_G; Empty_G, Force_L
Student # 22m
Scientific Fragments
Delayed-NMDQ
NoCUof_Force
Student # 23m
Alternative with Sci. Frag.
Delayed-NMDQ
Dist_L; Color; Dense_L; Uni_G Move_S; NoCUof_Force
130
Summary The 19 of the 23 (82.6%) RBTw/MR students started with less scientific conceptual understandings of the PNM. Nonetheless, 8 of these 19 students (34.7% in whole class) developed the targeted conceptual understandings of scientific understanding or scientific fragments after the instruction, while other 8 of these 19 students (34.8% in whole class) progressed to the scientific with alternative fragments category. During a three-month period following the intervention, half of the 8 RBTw/MR group students (17.4%) who developed the targeted conceptual understandings remained stable, whereas other half of them regressed to the scientific fragments or scientific with alternative fragments category. In general, 34.7% (8 of the 23) of the RBTw/MR students still held on to their scientific understandings of the PNM, and 43.6% (10 of the 23) of the RBTw/MR students exhibited mostly scientific conceptions in their explanations with at most three different alternative conceptions, which placed them in scientific with alternative fragments category. Individual students who displayed the same type of conceptual understandings at the beginning of the study followed different conceptual pathways throughout the study from the pretest to the post to the delayed posttest. The following section discusses each one of the conceptual pathways that individual group of the RBTw/MR students showed over time.
131
The RBTw/MR Group Students’ Conceptual Pathways of the PNM Question 2.1: How does the conceptual understanding of high school students on the aspects of the PNM change from preinstruction to post and to delayed posttest administered three-months after the RBTw/MR instruction? The individual students’ conceptual understandings of the PNM in each group (RBTw/MR and RBT) demonstrated diverse patterns from the pretest to the post to the delayed posttest. These unique patterns in students’ conceptual understandings of the PNM were called conceptual pathways that characterized their “learning routes along which students pass[ed] in developing understanding” of the PNM from the beginning of the instructional interventions to the posttest to the time of the delayed posttest (Scott, 1992, p.221). Nine different conceptual pathways were recognized in the RBTw/MR group. These conceptual pathways were hierarchically arranged from radical progress to no progress, and they numbered from 1 to 9 in the same way as they were arranged. A summary of the conceptual pathways can be seen in Table 4.5. The subsequent sections discuss each one of these conceptual pathways distinguished within the RBTw/MR group. The typical patterns identified in the RBT students’ conceptual pathways, which were a subset of the 9 conceptual pathways that depicted the RBTw/MR students’ conceptual understandings of the PNM over time, are described in the second section of this chapter.
132
Conceptual Pathways
RBTw/MR
RBT
Conceptual Pathway 1
Radical progress and either stability or slight decay Radical progress with moderate decay Moderate progress and stable
NA
Conceptual Pathway 2 Conceptual Pathway 3 Conceptual Pathway 4
NA NA
Moderate progress with full decay Slight progress and stable
NA
NA
Conceptual Pathway 7
Slight progress with slight decay Slight progress with full decay
Conceptual Pathway 8
Stable with slight progress
Slight progress with full decay NA
Conceptual Pathway 9
No progress
No progress
Conceptual Pathway 5 Conceptual Pathway 6
Slight progress and stable
Table 4.5: Summary of the identified conceptual pathways for each group.
Conceptual pathway 1: Radical progress and either stability or a slight decay If students developed a scientific understanding by advancing their conceptual understandings of the PNM three or more categories in reference to their initial types of conceptual understandings, the nature of the conceptual development was characterized as radical progress. The upper two conceptual understanding categories in the tables below (e.g., Table 4.6) were shaded to make it easy to notice if students’ conceptual understandings progressed to the targeted conceptual understanding categories of scientific or scientific fragments during the course of the study.
133
Pre Post Scientific
4
Sci. Frag.
Delayed 3 1
Sci. w/Alt.Frag Alt. w/Sci.Frag.
4
Alternative Frag. No Understanding
Table 4.6: Conceptual pathway 1 within the RBTw/MR group (Students 12m, 16m, 17m, 22m). As can be seen in Table 4.6, four of the RBTw/MR students (numbers 12m, 16m, 17m, 22m) entered the instruction with alternative understanding with scientific fragments (refer back to Table 4.1). Even though all four students were able to perceive matter as being discrete particles in the three states of matter on the pretest, they all held a combined set of the alternative conceptions about various aspects of the PNM. For example, the arrangement of particles in the solid and liquid states, the distances between the particles of liquids, the existence of attraction forces between the particles of matter and the presence of nothing between the particles of matter (refer back to Table 4.1). After the instruction, these four RBTw/MR students raised their types of conceptual understandings of the PNM three categories, developing a scientific understanding of the PNM, which can be described as radical progress. Three-months following the RBTw/MR instruction, three of the RBTw/MR students (numbers 12m, 16m, 17m) exhibited stability in their conceptual understandings of the PNM by not changing over
134
time. Yet, student 22m regressed back one category to scientific fragments, indicating a slight decay. Student 12m provides a typical example for this group in which his conceptual understanding showed progression toward a scientific understanding on the posttest and then remained stable on the delayed posttest. As shown in Figure 4.1 below, student 12m was not able to pictorially show the distinctive patterns for the arrangement of particles in the three states of matter on the pretest. In his picture, the particles were randomly arranged, looking alike for all three states of matter. In addition, he offered no verbal explanation for the arrangement of particles on the pretest. After his involvement in the RBTw/MR instruction, he not only pictorially illustrated the unique patterns in the arrangement of the particles in the three states of matter, but also related his explanation of the arrangement of particles to the existing forces of attraction between the particles. His posttest explanation of the arrangements of the particles stated that (see Figure 4.1): Gases are the most spread out of the three phases, because there is almost no attraction between the particles (SciForce_Arr_Dist_G). There is some attraction between the [liquid] particles so that they are … unorganized, but all close together (SciForce_Arr_Dist_L). Solids have the most attraction of the three phases, so, particles in solid state are organized and do not lose their shape (SciForce_Arr_S) (Student 12m, Post-NMDQ-q3). Three-months after the RBTw/MR instruction, his scientific verbal and pictorial responses regarding the arrangement of particles were consistent with his posttest responses (see Figure 4.1). Student 12m said, In the gas phase, the particles are not attracted to each other, so they bounce around never attaching to one another (SciForce_Arr_G). The [liquid] particles are all touching with a loose attraction (SciForce_Dist_L). In a solid, the particles are all very attracted to each other, so they stay in an organized way (SciForce_Arr_S) (Student 12m, Delayed-NMDQ-q3). 135
Gas
Liquid
Solid
Gas
Liquid
Solid
Pretest (NMDQ-q1)
Posttest (NMDQ-q3)
(SciArr_G_L, AltArr_S)
(SciArr_G_L_S)
Gas
Liquid
Solid
Delayed Posttest (NMDQ-q3) (SciArr_G_L_S)
Figure 4.1: Drawings that represent the student 12m’s conceptions of the arrangement of particles in the three states of matter.
Student 22m was another student who progressed to the scientific understanding on the posttest then regressed to scientific fragments category with a slight decay in his conceptions of the PNM over a three-month period. Student 22m held a conception of the discontinuity of matter prior to the RBTw/MR instruction, but he also held four commonly observed alternative conceptions as well (see Table 4.1). For instance, he perceived the distances between the particles of liquids as intermediate between the solid and the gas states, [e.g., “there is still some distance among particles of liquids” (AltDist_L) (Pre-NMDQ-q3)]. He also considered the attraction forces that exist between the particles as chemical bonds. Moreover, he believed in the existence of “other stuff” between the particles of oxygen gas, and he recognized the particles of solids as motionless, [e.g., “they have almost no movement” (AltMove_S) (Pre-NMDQ-q8)]. None of these identified alternative conceptions showed up in student 22m’s responses after the RBTw/MR instruction, giving rise to development of scientific conceptions of the PNM. The verbal and pictorial responses that he provided on the posttest in the context of explaining the melting of a solid exemplify the change that he achieved in his development of a scientific conception. He explained that particles of 136
solids are closely packed “because of a strong attraction forces” (Post-NMDQ-q8) that exist between the particles. He also called these forces “physical bonds” (SciForce_S). Moreover, student 22m said, “the particles of a solid loose [sic] their ability to stay orderly, when it turns into a liquid, but they [liquid particles] are still as compact as a solid (SciDist_L) (see Figure 4.2) and have more motion than particles of a solid (SciMove_S_L)” [Post-NMDQ-q8]. Three-months after the RBTw/MR instruction, even though student 22m came up with the very similar pictorial representation of melting of a solid as he drew on the posttest (see Figure 4.2), his explanation for what happens to the particles of a solid when it melts was limited to the change that occurs in the motion of particles. He said, when a solid turns into a liquid, “some structure is lost, and liquid particles have more motion than a solid, but less than a gas (SciMove_S_L_G)” [Post-NMDQ-q8]. Even though he was specifically asked about what keeps particles of solids close together in the same context—melting on the delayed posttest, he failed to provide an explanation for that specific question.
Posttest (NMDQ-q8)
Delayed Posttest (NMDQ-q8)
(SciArr_Dist_L)
(SciArr_Dist_L)
Figure 4.2: Drawings that represent student 22m’s conceptions of melting of a solid.
137
Conceptual pathway 2: Radical progress with a moderate decay Radical progress was recorded in three of the RBTw/MR students’ (3m, 5m, 9m) conceptual understandings of the PNM on the posttest (see Table 4.7). These three students’ conceptual understandings of the PNM then indicated a moderate decay on the delayed posttest. One students’ conceptual understanding (number 9m) in this conceptual pathway group was characterized as alternative fragments before the RBTw/MR instruction. He viewed matter as continuous in the three states of matter and held alternative conceptions about the aspects of the PNM that involves the existence of nothing between the particles of matter, the relative spacing between the particles of three states of matter and the uniform distribution of gas particles. He also exhibited no evidence of understanding any other aspects of the PNM. After his engagement in the RBTw/MR instruction, his conceptual understanding fulfilled the criteria established for a scientific understanding, demonstrating radical progress. He moved from the alternative fragments category to the scientific understanding category on the posttest.
Pre Scientific
Post
Delayed
3
Sci. Frag. Sci. w/Alt.Frag
3
Alt. w/Sci.Frag.
2
Alternative Frag.
1
No Understanding
Table 4.7: Conceptual pathway 2 within the RBTw/MR group (Students 3m, 5m, 9m). 138
From a scientific standpoint, gases are uniformly distributed in a closed container independent of the change in the amount of gases. On the pretest, student 9m believed that when half of the gas is released from the closed flask, the remaining gas would stay at the bottom half of the flask (e.g., “The air molecules are fully bouncing around in the compacted area [before releasing]. The pressure goes down and the air molecules stop bouncing around as much [after releasing]. The air sinks to the bottom [AltUni_G]” (PreNMDQ-q2). In the post interview, his response to the question about what happens to the gas particles when half of the gas is pumped out from the closed flask follows (see Figure 4.3): Hmm, for the first container, the gas is so compressed in just one container, and then, …when the gas is released, like there is less gas in the flask, which can move around, …. And, when it is not closed in or compressed, it can freely move out of the container (SciMove_Uni_G) (Student 9m, Post-Interview). On the delayed posttest, student 9m retained his conceptual understanding of the uniform distribution of gases (see Figure 4.3), whereas his scientific conception of the distances between particles of liquids reverted to alternative understanding (see Figure 4.4 and Table 4.4). This particular deterioration in his conception of the distances between liquid particles placed his overall conceptual understanding of the PNM in the scientific understanding with alternative fragments category three-months after the RBTw/MR instruction.
139
Posttest (NMDQ-q2)
Delayed Posttest (NMDQ-q2)
(SciUni_G)
(SciUni_G)
Figure 4.3: Drawings that represent student 9m’s conceptions of the uniform distribution of gases.
Posttest (NMDQ-q3)
Delayed Posttest (NMDQ-q3)
(SciDist_G_L_S)
(SciDist_G_S; AltDist_L)
Figure 4.4: Drawings that represent student 9m’s conceptions of the relative spacing between the particles in the three states of matter.
The other two students’ (numbers 3m, 5m) conceptual understandings met the criteria of alternative understanding with scientific fragments, before the RBTw/MR instruction (see Table 4.7). They either held alternative conceptions about the arrangements of and the distances between the particles or showed no understanding of several aspects of the PNM (e.g., the discrete nature of matter [refer back to Table 4.1]). Following the RBTw/MR instruction, these two students conceptually moved to the scientific understanding category, indicating radical progress as did student 9m. Threemonths after the instruction, students 3m and 5m and student 9m, as articulated in the 140
previous section, regressed to the scientific understanding with alternative fragments category with a moderate decay in their conceptual understandings of the PNM. In fact, if we take a closer look at their understandings of the PNM over a three month period, these students (numbers 3m, 5m, 9m) either encountered difficulty with one of the aspects of the PNM such as the motion of particles in the solid state, the uniform distribution of particles, the distances between particles of liquids or fell short of generating scientific explanation for one aspect of the PNM (e.g., the existence of attraction forces between particles [refer back to Table 4.4]). For instance, neither student 3m nor student 5m demonstrated any evidence of understanding the movement of solid particles on the pretest (see Table 4.1). However, they both held a scientific understanding of the motion of solid particles on the posttest, [e.g., “they [solid particles] are attracted to each other and slow moving (SciMove_S)” (Student 3m, Pre-NMDQ-q8)]. Student 3m, then, held alternative conception about the motion of particles on the delayed posttest, [e.g., “They [solid particles] are strongly drawn to one another and do not move (AltMove_S)” (Delayed-NMDQ-q8)]. Yet, student 5m’s conception of the motion of solid particles seemed to be extinguished, indicating no evidence of understanding this particular concept on the delayed posttest. In summary, three students (numbers 3m, 5m, 9m) in the RBTw/MR group restructured their conceptual understandings of the PNM following the instruction and showed radical progress toward a scientific understanding. These three students’ conceptual understandings, then, regressed to the scientific understanding with alternative fragments category, exhibiting a moderate decay in their conceptual understandings. 141
Conceptual pathway 3: Moderate progress and stable If students achieved either a scientific understanding or scientific fragments by initially beginning with the types of conceptual understandings of scientific with alternative fragments or alternative with scientific fragments, the change in these students’ conceptual understandings of the PNM is defined as moderate progress. As shown in Table 4.8, four students (numbers 1m, 2m, 6m, 11m) in the RBTwMR group held scientific understandings with alternative fragments before they were engaged in the instruction. The most common alternative conception observed among these students involves the distances between particles of a liquid (refer back to Table 4.1). They all believed that the particles of liquids are somewhat further apart than the particles of solids. The other alternative conceptions they held on the pretest consisted of considering the particles of solids motionless and believing in the existence of something between the particles of gases. The number of alternative conceptions that these students held ranged from one to three prior to the intervention. These four students demonstrated moderate progress with two-category progression in their conceptual understandings of PNM from the scientific with alternative fragments to the scientific understanding category after the RBTw/MR instruction. In the long-term, all four of the students maintained their scientific understandings, exhibiting stability in their scientific conceptions of the PNM.
142
Pre Scientific
Post
Delayed
4
4
Sci. Frag. Sci.w/Alt.Frag
4
Alt. w/Sci.Frag. Alternative Frag. No Understanding
Table 4.8: Conceptual pathway 3 within the RBTw/MR group (Students 1m, 2m, 6m, 11m).
The change in student 1m’s conceptions of the PNM distinctly represents this group of students. For example, student 1m described the distances between the particles of liquids as “closer together” (AltDist_L) in her explanation on the pretest, but the distances between the particles of a liquid looked even further apart like the spacing that she showed between the particles of a gas (see Figure 4.5). In the post interview, she was able to make an apparent distinction between the distances of the particles in three states of matter. Her pictorial representation was in accord with her verbal description of the distances between the particles of matter (see Figure 4.5). Student 1m stated that: The solid particles are closer together (SciDist_S) and… they just kind of vibrate (SciMove_S). And then, in the liquid phase, the particles are just as close together as solid particles (SciDist_L), but they can move pass each other. The gas, the particles are far apart (SciDist_G), they move very quickly (SciMove_G) [PostInterview].
143
On the delayed posttest, her verbal and pictorial responses regarding the question of the arrangement of and the distances between the particles in three states of matter were similar to her responses in the post interview (see Figure 4.5). Student 1m said Gas particles are far apart (SciDist_G). They move quickly past each other (SciMove_G) and are irregularly arranged. (SciArr_G). They have no definite shape. Liquid particles are close together (SciDist_L), but could still move past each other (SciMove_L). They (liquid) are irregularly arranged (SciArr_L) and have no definite shape. Solid particles are also close together (SciDist_S) and regularly arranged (SciArr_S). The particles cannot move past each other, but can vibrate (SciMove_S), and it has a definite shape and volume [Delayed-NMDQq3].
Pretest (NMDQ-q1)
(AltDist_L)
Posttest (NMDQ-q3)
Delayed Posttest (NMDQ-q3)
(SciDist_G_L_S)
(SciDist_G_L_S)
Figure 4.5: Drawings that represent student 1m’s conceptions of the relative spacing between the particles in the three states of matter.
Conceptual pathway 4: Moderate progress with a full decay Student 21m was the only participant who pursued conceptual pathway 4 in which the student first exhibited moderate progress by moving from alternative understanding with scientific fragments to scientific fragments after her involvement in the RBTw/MR instruction (see Table 4.9). Then, her conceptual understanding of the PNM fully decayed within a three-month period.
144
Pre
Post
Delayed
Scientific Sci. Frag.
1
Sci.w/Alt.Frag Alt. w/Sci.Frag.
1
1
Alternative Frag. No Understanding
Table 4.9: Conceptual pathway 4 within the RBTw/MR group (Student 21m).
Technically, the distances between the particles of liquids are considered to be similar to the distances between the particles of solids. Her understanding of this particular concept showed the characteristics of alternative conception on the pretest. She stated that “the particles [liquid particles] are closer together, but farther apart than solid state (AltDist_L)” [Pre-NMDQ-q3]. Based on her explanation, it seems that the spacing between the particles of liquids is in between the spacing between particles of solids and gases. On the posttest, her explanation about the distances between the liquid particles follows (see Figure 4.6): “Liquid particles are very close together (SciDist_L)” [PostNMDQ-q3]. On the same test, her drawings of the liquid state in the other contexts exhibited consistency with her verbal statement. Three-months following the RBTw/MR instruction, when she was directly asked about the distances between the particles of liquids, her response was in parallel with her verbal and pictorial representations on the posttest, [e.g., “Liquid particles are arranged randomly, but are very closely packed (SciDist_L)” (Post-NMDQ-q3; see Figure 4.6)]. However, when she was asked to draw 145
the particles of a liquid in other contexts, (e.g., dissolving of sugar) the distances between liquid particles appeared to be further apart compared to the distances between particles of a solid (see Figure 4.6).
Water
Posttest (NMDQ-q3) (SciDist_L)
Water
Sugar
Delayed Posttest (NMDQ-q3) (SciDist_L)
Water
Delayed Posttest (NMDQ-q4) (SciDist_S; AltDist_L)
Figure 4.6: Drawings that represent student 21m’s conceptions of the relative spacing between the particles of liquids.
Conceptual pathway 5: Slight progress and stable The one-category improvement toward a scientific understanding in students’ understandings of the PNM without developing targeted conceptual understandings of either scientific understanding or scientific fragments was characterized as slight progress. Six students (numbers 4m, 7m, 8m, 13m, 14m, 15m) in the RBTw/MR group showed evidence of slight progress in their types of conceptual understandings of the PNM following the intervention (see Table 4.10). Prior to the RBTw/MR instruction, the most frequently held alternative conceptions among these six students included the asymmetrical arrangement of solid particles (see Figure 4.7), considering the distances between the particles of liquids as in between solid and gas state. For example student 14m stated that “the arrangement is a little less loose than the gas but the particles aren’t extremely close but not extremely far 146
apart (AltDist_L)” [Pre-NMDQ-q3]. Another common alternative conception exhibited by these students was the existence of some material between particles of matter such as air, more gases, carbon or carbon dioxide.
Pre
Post
Delayed
6
6
Scientific Sci. Frag. Sci.w/Alt.Frag Alt. w/Sci.Frag.
6
Alternative Frag. No Understanding
Table 4.10: Conceptual pathway 5 within the RBTw/MR group (Students 4m, 7m, 8m, 13m, 14m, 15m).
Pretest (NMDQ-q1) (AltArr_S)
Posttest (NMDQ-q1) (SciArr_S)
Delayed Posttest (NMDQ-q1) (SciArr_S)
Figure 4.7: Drawings that represent student 4m’s conceptions of the arrangement of solid particles.
Although the number of alternative conceptions that these 6 students held on the pretest were not evidenced in their explanatory framework following the RBTw/MR instruction, they still held onto some alternative conceptions, varying in number between 147
one and three alternative conceptions (refer back to Table 4.3). Five of the 6 students exhibited scientific understandings of the arrangement of particles in their verbal and pictorial representations on the posttest (see Figure 4.7). However, only one student (student 15m) constructed a scientific understanding of the relative distances between particles of liquids (see Figure 4.8). The others (numbers 4m, 8m, 13m, 14m) who previously held alternative conceptions of this particular concept persisted in holding the same alternative conception after the RBTw/MR instruction (see Figure 4.8). Additionally, only half of the six students (numbers 4m, 7m, 14m) developed a scientific understanding of the existence of nothing between the particles of matter following the RBTw/MR instruction.
(Student 15m, Post-NMDQ-q3) (SciDist_S_L_G)
(Student 13m, Post-NMDQ-q3) (SciDist_S_G; AltDist_L)
Figure 4.8: Drawings that represent two of the RBTw/MR students’ conceptions of the relative spacing between the particles on the posttest.
These six of the RBTw/MR students’ conceptual understandings of the PNM were stable over a three-month period. For example, among these six students who developed a scientific understanding of the arrangement of solid particles maintained their conceptions (see Figure 4.7). Although student 15m sustained her scientific understanding of the distances between liquid particles, those who showed no change in their alternative conceptions of believing in the distances between liquid particles as 148
intermediate compared to the distances between particles of solids and gases continued retaining that nonscientific conception on the delayed posttest (see Figure 4.9).
(Student 15m, Post-NMDQ-q3)
(Student 13m, Delayed-NMDQ-q3)
(SciDist_S_L_G)
(SciDist_S_G; AltDist_L)
Figure 4.9: Drawing that represent two of the RBTw/MR students’ conceptions of the relative spacing between the particles on the delayed posttest.
Two specific alternative conceptions held by two of these six students call for attention and discussion here. For instance, on the pretest, student 15m showed no sign of holding a nonscientific understanding concerning the attribution of physical changes (i.e., color change) to the single particles. However, on the post interview, in the context of mixing of food coloring and water, she attributed the change in color of water to the single particles of water. The excerpt from her post interview follows: Researcher: Could you please explain your pictures in question 5? (see Figure 4.10) Student 15m: The first one, when they are just added, the particles are at the top, and there is more water particles, and after they sink to ground and take up the place of the water. Researcher: You put four molecules of food coloring in the first picture on the left, then, there are more than four molecules of food coloring in the second picture on the right. How would you explain that? Student 15m: I think the food coloring takes place of the water particles. That is why there are fewer water particles in the second picture (AltColor_L).
149
According to her explanation, water particles are replaced by the food coloring particles, while food coloring and water were mixing together. On the delayed posttest, she reiterated the same alternative understanding in a slightly different way. She supposed that particles of water are colored by particles of food coloring. She said, “in the first box, the food coloring is at the top, because it was just added, as time goes by the food coloring molecules slowly turn the water blue, but there are still some water molecules that aren’t colored in the solution (AltColor)” [PostNMDQ-Q5, see Figure 4.10]. It can be inferred that her explanations and drawings at the two data collection points apparently consisted of the pieces of both macroscopic and submicroscopic properties of matter. That is, she still interpreted the submicroscopic actions of matter based on the changes visible at the macroscopic level.
Posttest (NMDQ-q5)
Delayed Posttest (NMDQ-q5)
(AltColor_L, SciArr_Dist_L)
(AltColor_L, SciArr_Dist_L)
Figure 4.10: Drawings that represent student 15m’s alternative conceptions of the mixture of food coloring and water molecules at the submicroscopic level.
Another interesting alternative conception is related to the change in size of the particles. Even though student 7m exhibited no evidence of a nonscientific understanding of the change in sizes of particles on the pretest, as can be seen in his drawing of the particles for the water in three physical states on the posttest (see Figure 4.11), he 150
represented the size of the water particles small in the gas phase, and larger in the liquid and solid states. Similar to the previous case for student 15m, the macroscopic properties of matter appeared to interfere with his perceptions of the matter at the particulate level. He considered the particle sizes as larger for the physical states of matter that are tangible and visible such as with a solid and a liquid. However, he conceived of the size of the gas particles, at which water vapor is clear in color and unavailable to visual observations, as smaller relative to the particles sizes of the other physical states. The arrangement of particles in the solid state also looks unusual in his drawing as if they were squeezed and overlapped. This could be his way of visualizing the account that ‘the particles of solids are tightly packed and compacted’, which actually reflects his peers informal description of the solid state in class discussions.
Posttest (NMDQ-q3)
Delayed Posttest (NMDQ-q3)
(AltSize_S_L)
(AltSize_S_L)
Figure 4.11: Drawings that represent student 7m’s conceptions of the change in size of the particles in the three states of matter.
Conceptual pathway 6: Slight progress with a slight decay Only one student pursued this particular conceptual pathway, which included slight progress and then a slight decay. Student 18m’s conceptual understanding fit into no understanding category in the beginning of the RBTw/MR instruction (see Table 4.11). He did not show any evidence of understanding either the discontinuity of matter 151
in any physical states or the other relevant aspects of the PNM on the pretest (see Table 4.1). Although the conceptual progress he made appears to be two-category toward a scientific understanding, his conceptual understanding of the PNM predominantly included alternative conceptions. Thus, the progression in his conceptual understanding was recognized to be slight progress.
Pre
Post
Delayed
Scientific Sci. Frag. Sci.w/Alt.Frag Alt. w/Sci.Frag.
1
Alternative Frag. No Understanding
1 1
Table 4.11: Conceptual pathway 6 within the RBTw/MR group (Student 18m).
Following the RBTw/MR instruction, student 18m demonstrated an understanding of the discontinuity of matter (see Figure 4.12), including a few other aspects of the PNM such as the motion of particles. He said, “the food coloring molecules spread out in water (SciMove_L)” [Post-NMDQ-q5]. He also held some alternative conceptions such as believing in the existence of air between the particles of matter. This slight progress in his conceptions of the PNM elevated his type of conceptual understanding to the alternative with scientific fragments category.
152
Three-months after the RBTw/MR, his conceptual understanding fell back to the alternative fragments category by undergoing a slight decay. Regarding his drawing of matter as continuous in the solid state, his conception of the discontinuity of matter seems to have reverted back within this three-month period. Also, he still believed in the existence of air between the particles of matter and exhibited no understanding of other aspects of the PNM on the delayed posttest. Solid
Liquid
Gas
Pretest (NMDQ-q1)
Solid
Liquid
Gas
Posttest (NMDQ-q1)
(AltPart_S_L; NoCUPart_G)
(SciPart_S_L_G)
Solid
Liquid
Gas
Delayed Post (NMDQ-q1) (AltPart_S; SciPart_L_G)
Figure 4.12: Drawings that represent student 18m’s conceptions of the discrete nature of matter in the three states of matter.
Conceptual pathway 7: Slight progress with a full decay Two students (numbers 20m, 23m) displayed slight progress on the posttest by enhancing their type of conceptual understandings just one-category from alternative with scientific fragments to scientific with alternative fragments (see Table 4.12). As they move toward a scientific understanding, their conceptions of the PNM evolved, but some of their alternative conceptions, the conceptions which appeared to be resistant to change, continued to exist in their explanatory framework. In the long-term, the scientific conceptions that they held on the posttest about specific aspects of the PNM either regressed or were extinguished. Thus, these students’ types of conceptual understandings reverted back to their original conceptual understandings, exhibiting a full decay. 153
The verbal explanations and pictorial representations offered by student 23m exemplify the variations that these two students conceptually experienced at three data collection points. On the pretest, in the context of the phase change from gas to liquid, student 23m just referred to the changes that occur in the arrangement of and the distances between the particles of matter. She said, “the particles of a gas are so spread out very far apart, but in a liquid they come close together (SciDist_S_L)” [Pre-NMDQq3]
Pre
Post
Delayed
Scientific Sci. Frag. Sci.w/Alt.Frag Alt. w/Sci.Frag.
2 2
2
Alternative Frag. No Understanding
Table 4.12: Conceptual pathway 7 within the RBTw/MR group (Student 20m, 23m).
In the post interview, student 23m’s explanation for the condensation of a gas included almost all aspects of the PNM with appropriate comparisons between two states of matter (see Figure 4.13). However, she was not able to develop a scientific understanding about the concept that the distances between the particles of liquids are similar to the distances between the particles of solids. Therefore, her overall type of conceptual understanding was characterized as scientific with alternative fragments after the RBTw/MR instruction. The excerpt from the post-interview follows: 154
Researcher: Consider that you have a flask filled with air, and it is cooled down until it liquefies. How does the behavior of gas particles change when a gas turns into a liquid? Student 23m: When it is just in the flask, the gas particles are floating around like a gas would behave, and then, after it is liquefied, I believe that the particles slow down and come closer together (SciMove_L_G). Researcher: You said that particles of a gas come close together when it turns into a liquid, what keeps these particles close together? Student 23m: When being in a liquid phase, … the attraction forces brings them closer together (SciForce_L). Researcher: How strong is the attraction among the particles in the liquid state? Student 23m: It is like in the middle, like the attraction is like really strong and pulls them together, but it is not strong enough to keep them together like as if it were a solid, like holding them really really close together (SciForce_S_L_G). On the delayed posttest, student 23m’s explanation of the condensation of a gas was very similar to the one she provided on the pretest, [e.g., “they [the gas particles] come close together (SciDense_L)” [Delayed-NMDQ-q7]. In her picture, the particles appeared to be closer together, but they filled up the whole flask as if it was a gas (see Figure 4.13). In this instance, she ignored the phenomenon that the particles mostly accumulate at the bottom of the flask when a gas turns into a liquid. In a broad sense, it appears that the conceptual path that she accomplished indicates growth and then deterioration in her understanding of the PNM over three data collection points.
Posttest (NMDQ-q7)
Delayed Posttest (NMDQ-q7)
(SciArr_Dist_L)
(AltDense_L)
Figure 4.13: Drawings that represent student 23m’s conceptions of condensation of a gas.
155
Conceptual pathway 8: Stable with slight progress Student 10m was one of the two RBTw/MR students who showed no progress on the posttest, and then on the delayed posttest his conceptual understanding of the PNM identified to be slight progress. Even though student 10m held a scientific understanding of the discontinuity of matter before the intervention, he encountered difficulty with understanding several other aspects of the PNM (see Table 4.1). Some of those scientifically incompatible conceptions showed up once again on the posttest with additional different alternative conceptions such as representing rigid lines (bonds) between the particles of liquids and solids. Thus, his type of conceptual understanding remained the same from the pretest to posttest with no progress (see Table 4.13).
Pre
Post
Delayed
Scientific Sci. Frag. Sci.w/Alt.Frag Alt. w/Sci.Frag.
1 1
1
Alternative Frag. No Understanding
Table 4.13: Conceptual pathway 8 within the RBTw/MR group (Student 10m).
Despite the recurrence of the similar alternative conceptions on the delayed posttest as the conceptions identified on the posttest (e.g., the arrangement of and the distances between the liquid particles), student 10m displayed slight progress on the 156
delayed posttest with the change of one of his alternative conceptions, which included the representation of rigid lines (bonds) between the particles of liquids and solids (see Figure 4.14). The conceptual path that he followed about this specific conception was interesting indeed. On the pretest, while representing the three states of matter, he illustrated no rigid bonds (or lines) between particles of solids and liquids (see Figure 4.14). On the posttest, he sketched rigid lines (bonds) between the particles of solids and liquids whereas there were no rigid lines between the particles of gases. On the delayed posttest, his perception of representing bonds between the particles of solids and liquids changed, but his representation of the arrangement of the particles in the solid and liquid states persisted over a three-month period.
Liquid
Solid
Liquid
Pretest (NMDQ-q1)
(SciPart_L_S)
Solid
Liquid
Solid
Posttest (NMDQ-q3)
Delayed Posttest (NMDQ-q3)
(SciPart_L_S; AltBond_S_L)
(SciPart_L_S)
Figure 4.14: Drawings that represent student 10m’s conceptions of the existence of bonds between the particles of liquids and solids.
Conceptual pathway 9: No progress No progress was identified in one of the students’ conceptual understanding of the PNM from the pretest to the post to the delayed posttest (see Table 4.14). Before starting the RBTw/MR intervention, when student 19m was asked about how matter would look if he was able to see it at the submicroscopic scale, he showed alternative conception in perceiving matter as being discrete particles in the three physical states (see Figure 4.15). 157
Additionally, he demonstrated no evidence of understanding the major aspects of the PNM other than the motion of the particles in liquid and gas states [e.g., “gas particles move faster than the liquid; the ice particles do not move (SciMove_L_G, AltMove_S)” Pre-NMDQ-q3] and the existence of a vacuum between the particles (see Table 4.1). After the RBTw/MR instruction, he still encountered conceptual difficulty with the notion of the discrete nature of matter, because he continued to believe in the idea of continuous matter in the solid state (see Figure 4.15). Overall, no major conceptual improvement was noticed in his conceptual understanding of the aspects of the PNM from the pretest to the posttest.
Pre
Post
Delayed
1
1
1
Scientific Sci. Frag. Sci.w/Alt.Frag Alt. w/Sci.Frag. Alternative Frag. No Understanding
Table 4.14: Conceptual pathway 9 within the RBTw/MR group (Student 19m). As with the pretest, his verbal explanations on the posttest included very short explanations and indicated no associations among the constitutive concepts of the PNM. For example, in the context of mixing of two gases, to describe what happens to the particles of two gases when the valve opens to connect two gas-filled containers, he said, “all colored gas spreads to the air”. This is not a nonscientific understanding, but includes 158
no detailed explanation and particle ideas that show evidence for his scientific understanding of the phenomenon at the submicroscopic scale. On the delayed posttest, the alternative conceptions that were distinguished on the posttest reemerged in his responses on the delayed posttest with no change in his perception of the discrete nature of matter in the solid state (see Table 4.3 and Table 4.4). Solid
Liquid
Gas
Pretest (NMDQ-q1)
(AltPart_S_L_G)
Solid
Liquid
Gas
Solid
Liquid
Gas
Posttest (NMDQ-q1)
Delayed Posttest (NMDQ-q1)
(AltPart_S; SciPart_L_G)
(AltPart_S; SciPart_L_G)
Figure 4.15: Drawings that represent student 19m’s conceptions of the discrete nature of matter. Summary From the beginning to the end of the RBTw/MR instruction, almost all students (91%) in this group made progress toward a scientific understanding ranging from radical progress to slight progress. Three months after the posttest, while more than half of these students (56%) maintained their types of conceptual understandings of the PNM, the remaining 44% of the students reverted to at least one category back in comparison to the types of conceptual understanding that they exhibited on the posttest. The following section presents the RBT group students’ types of conceptual understandings of the PNM, before, immediately after, and three-months after the instruction, including discussion as to how the RBT group students’ conceptual understandings changed over time. 159
The RBT Group Students’ Conceptual Understandings of the PNM
Before the RBT Intervention Question 1a.2: What are the types of conceptual understandings held by high school students about the aspects of the PNM just before starting the RBT instruction?
Participants
Type of Conceptual Understanding
Data Sources
Alternative Conceptions
Student # 1
Alternative Fragments
Pre-NMDQ
Part_S_L; Color_L; NoCUof_Move & Force &Empty &Arr & Dist & Uni_L; Dense_L
Student # 2
Alternative with Sci. Frag.
Pre-NMDQ
Dist_L; Force_S_L; NoCUof_Part & Arr & Empty & Uni_Dense_L
Student # 3
Alternative with Sci. Frag.
Pre-NMDQ
Student # 4
Alternative with Sci. Frag.
Pre-NMDQ
Dist_L; Empty_G; NoCUof_Part & Force & Arr_S_L_G & Move_S & Dense_L Part_S; Dist_L; Move_S; Uni_G; NoCUof_Force
Student # 5
Scientific with Alt. Frag.
Pre-NMDQ
Student # 6
Alternative with Sci. Frag.
Pre-NMDQ
Student # 7
Alternative with Sci. Frag.
Pre-NMDQ
Part_S_G; Dist_L; Uni_G; Force_G; NoCUof_Dense_L_G
Student # 8
Alternative with Sci. Frag.
Pre-NMDQ
Arr_S; Dist_S_L; Uni_G; Force_S
Student # 9
Alternative Fragments
Pre-NMDQ
Part_S_L; Dist_S_L_G; Dissolving; NoCUof_Part_G & Move & Force & Empty & Arr & Dense & Uni
Student # 10
Alternative with Sci. Frag.
Pre-NMDQ
Part_S; Empty_G; NoCUof_Force & Dense_L & Move_S & Dense_L
Student # 11
Alternative with Sci. Frag.
Pre-NMDQ
Dist_L; Move_S; Dissolving; NoCUof_Part & Force & Empty & Uni_S_L_G & Dense_L
Dist_L; Dissolving; NoCUof_Force & Move_S & Dense_L Part_S_L_G; Dist_L; Color_L; Empty; NoCUof_Force & Move_S_L; Dense_L_G
Continued. Table 4.15: Students’ types of conceptual understandings before the RBT. 160
Table 4.15 continued.
Participants
Type of Conceptual Understanding
Data Sources
Student # 12
No Understanding
Pre-NMDQ
Student # 13
Scientific with Alt. Frag.
Pre-NMDQ
Part_S; Move_S; Dist_L; NoCUof_Force
Student # 14
Scientific with Alt. Frag.
Pre-NMDQ
Dist_L; NoCUof_Force & Dense_L
Student # 15
Alternative with Sci. Frag.
Pre-NMDQ
Student # 16
Scientific with Alt. Frag.
Pre-NMDQ
Part_S; Dist_L; Move_S; NoCUof_Force; Dense_L Dis_L
Student # 17
Alternative with Sci. Frag.
Pre-NMDQ
Student # 18
Scientific with Alt.Frag.
Pre-NMDQ
Student # 19
Alternative with Sci. Frag.
Pre-NMDQ
Alternative Conceptions
Part_S_L_G; Dist_L; Color_G; Force_L; Empty_G; NoCUof_Move_S Arr_S; Dist_L; NoCUof_Force Arr_S; Dist_L; Move_S; Color_G; Empty_G; NoCUof_Force
All students in the Reform-Based Teaching group, like the RBTw/MR students, held a number of alternative conceptions about different aspects of the PNM in various combinations before the intervention. Since none of the student put all eight pieces of the PNM together, placed them in less scientific types of conceptual understanding categories. Thus, none of the student’s responses on the pretest was classified as scientific or scientific fragments. Students’ types of conceptual understandings before the RBT instruction are listed in Table 4.15, indicating the alternative conceptions or no conceptual understandings (NCU) that each student held along with the data sources that were considered in identification of students’ type of conceptual understandings. Similar to the frequency proportions obtained by the RBTw/MR group (82.5%), a large number (73.7%) of the RBT students’ preinstruction conceptual understandings of 161
the PNM fit into the conceptual understanding categories of no understanding, alternative fragments, and alternative with scientific fragments (see Table 4.15). In particular, 11 of the 19 (57.9%) RBT students (numbers 2, 3, 4, 6, 7, 8, 10, 11, 15, 17, 19) were classified as alternative with scientific understanding, 2 of the 19 (10.5%) as alternative fragments, and 1 of the 19 (5.3%) as no understanding.
Pretest
Posttest
Delayed Posttest
Scientific
0 (0%)
0 (0%)
0 (0%)
Scientific fragments
0 (0%)
0 (0%)
0 (0%)
Scientific w/alternative frag.
5 (26.3%)
11 (57.9%)
8 (42.1%)
Alternative w/scientific frag.
11 (57.9%)
5 8 (26.3 %) (42.1%)
Alternative Frag.
2 (10.5%)
3 (15.8%)
3 (15.8%)
No Understanding
1 (5.3%)
0 (0%)
0 (0%)
Total
19 (100%)
19 (100%)
19 (100%)
Table 4.16: Summary of conceptual understandings for the RBT group.
After the RBT Intervention Question 1b.2: What are the types of conceptual understandings held by high school students about the aspects of the PNM just after completion of the RBT instruction? 162
Immediately after the RBT instruction, the frequency distributions of the types of conceptual understandings for the students in this group were quite different from the frequency distributions of the RBTw/MR students (see Table 4.2 and Table 4.16). Categories of conceptual understandings after the RBT instruction are presented in Table 4.17, including the data sources and notes about alternative conceptions and no conceptual understandings (NCU) held by each student. In general, none of the RBT students provided responses that met the eight scientific criteria, thus, no student in this group moved to the scientific understanding category. The upper limit of the types of conceptual understandings, scientific understanding with alternative fragments, remained the same as before the RBT instruction. Only 6 of the 19 RBT students (31.6%) proceeded to the scientific understanding with alternative fragments. The students (numbers 5, 3, 14, 16, 18) who already held scientific understanding with alternative fragments before the RBT instruction maintained the same type of conceptual understanding but changed few of their alternative conceptions in favor of the scientific views. Specifically, 11 of the 19 RBT students (57.9%) were identified as scientific with alternative fragments after the RBT instruction. Five of the 19 (26.3%) RBT students’ conceptual understandings met the criteria established for alternative with scientific fragments category. Three of the 19 (15.8%) RBT students’ conceptual understandings were demonstrated the features of the alternative fragments category.
163
Participants
Type of Conceptual Understanding
Student # 1
Data Sources
Alternative Conceptions
Alternative Fragments
Post-NMDQ & Interview
Student # 2
Scientific with Alt. Frag.
Post-NMDQ
Arr_L; Dist_S_L; Move_S; Force_S_L; Empty_G; Color_L; Bond_S_L Dist_L; Size_S; NoCUof_Force
Student # 3
Scientific with Alt. Frag.
Dist_L; Bond_S_L
Student # 4
Scientific with Alt. Frag.
Post-NMDQ & Interview Post-NMDQ
Student # 5
Scientific with Alt. Frag.
Post-NMDQ
Dist_L; Uni_G; Bond_S_L; NoCUof_Force & Dense_G
Student # 6
Scientific with Alt. Frag.
Dist_L, Bond_L
Student # 7
Alternative with Sci. Frag.
Student # 8
Scientific with Alt. Frag.
Post-NMDQ & Interview Post-NMDQ & Interview Post-NMDQ
Student # 9
Alternative Fragments
Post-NMDQ
Student # 10
Scientific with Alt. Frag.
Post-NMDQ
Part_L; Arr_L; Dist_L; Size_S; NoCUof_Move & Force & Empty_G & Uni_Dense_L Dist_L; Dense_L; Size_S
Student # 11
Alternative with Sci. Frag.
Post-NMDQ
Student # 12
Alternative Fragments
Post-NMDQ
Student # 13
Scientific with Alt. Frag.
Post-NMDQ
Student # 14
Scientific with Alt. Frag.
Dist_L, Bond_S_L
Student # 15
Alternative with Sci. Frag.
Post-NMDQ & Interview Post-NMDQ
Student # 16
Scientific with Alt. Frag.
Post-NMDQ
Dist_L; Empty_L
Student # 17
Alternative with Sci. Frag.
Post-NMDQ
Dist_L; Dense_L_G; Bond_L_S, Color_L; NoCUof_Force
Student # 18
Scientific with Alt. Frag.
Post-NMDQ
Dist_L; Dense_L, NoCUof_Force
Student # 19
Alternative with Sci. Frag.
Post-NMDQ
Dist_L; Move_S; Color_L; Empty_L; NoCUof_Force
Arr_L; Dist_L; Empty_S_L; NoCUof_Dense_L
Dist_L; Arr_L; Color_L; Bond_L; NoCUof_Force Arr_L; Dist_L; Force_S_L
Arr_S; Dist_S_L; Color_L; NoCUof_Move & Force & Empty & Dense_L Part_L_G; Dist_L; NoCUof_Part_S & Arr & Move & Force & Empty & Uni& Dense Dist_L; Force_S_L; Bond_S_L
Part_S; Dist_L; Dense_L_G; Empty_L; NoCUof_Force
Continued. Table 4.17: Students’ types of conceptual understandings shortly after the RBT. 164
Three-Months after the RBT Intervention Question 1c.2: What are the types of conceptual understandings held by high school students about the aspects of the PNM three-months after completion of the RBT instruction? Three-months after the instruction, the RBT students’ conceptual understandings of the PNM deteriorated considerably (see Table 4.16 above). Categories of conceptual understandings three-months after the RBT instruction are summarized in Table 4.18, including the data sources, the types of alternative conceptions and no conceptual understandings (NCU) held by each student. The frequencies of types of conceptual understandings three-months after the RBT were very similar to the frequencies found on the pretest (see Table 4.16). Eight (numbers 3, 4, 5, 8, 13, 14, 16, 18) of the 19 RBT students (42.1%) held a scientific understanding with alternative fragments. In fact, 5 of these students (26.4%) held the same type of conceptual understanding before the RBT instruction and again threemonths after the RBT instruction. Eight (numbers 2, 6, 7, 10, 11, 15, 17, 19) of the 19 RBT students (42.1.9%) were identified as holding an alternative understanding with scientific fragments, and 3 (numbers 1, 9, 12) of the 19 (15.8%) RBT students held alternative fragments.
165
Participants
Type of Conceptual Understanding
Data Sources
Alternative Conceptions
Student # 1
Alternative Fragments
Delayed-NMDQ
Student # 2
Alternative with Sci. Frag.
Delayed-NMDQ
Arr_L; Dist_S_L; Move_S; Empty_G; Bond_S_L; Uni_G; NoCUof_Force Part_L; Dist_L; Size_S; Empty_L; NoCUof_Force
Student # 3
Scientific with Alt. Frag.
Delayed-NMDQ
Dist_L; Bond_S_L; Force_L
Student # 4
Scientific with Alt. Frag.
Delayed-NMDQ
Arr_L; Dist_L
Student # 5
Scientific with Alt. Frag.
Delayed-NMDQ
Arr_L; Dist_L; Dense_L; NoCUof_Force
Student # 6
Alternative with Sci. Frag.
Delayed-NMDQ
Part_S_L_G; Arr__S_L; Dist_L
Student # 7
Alternative with Sci. Frag.
Delayed-NMDQ
Arr_L; Dist_L; Uni_G; Bond_L; Dense_L_G
Student # 8
Scientific with Alt. Frag.
Delayed-NMDQ
Arr_L; Dist_L; NoCUof_Force
Student # 9
Alternative Fragments
Delayed-NMDQ
Part_S_L_G; Empty_G; NoCUof__Arr & Dist & Move_S & Force & Uni_L & Dense_L_G
Student # 10
Alternative with Sci. Frag.
Delayed-NMDQ
Part_S; Arr_L; Dist_L; Dense_L; NoCUof_Force
Student # 11
Alternative with Sci. Frag.
Delayed-NMDQ
Part_L; Dist_L; NoCUof_Force & Empty_G & Move_L_S
Student # 12
Alternative Fragments
Delayed-NMDQ
Part_S_L; NoCUof_Arr&Move& Force & Empty_G & Uni & Dense
Student # 13
Scientific with Alt. Frag.
Delayed-NMDQ
Dist_L; Move_S; Force_S
Student # 14
Scientific with Alt. Frag.
Delayed-NMDQ
Dist_L
Student # 15
Alternative with Sci. Frag.
Delayed-NMDQ
Student # 16
Scientific with Alt. Frag.
Delayed-NMDQ
Part_S_L; Arr_S; Dist_L; Dense_L; NoCUof_Force & Empty Dist_L; Empty_L; Size
Student # 17
Alternative with Sci. Frag.
Delayed-NMDQ
Bond_S_L; Arr_L; Dist_L; Dense_L; NoCUof_Force
Student # 18
Scientific with Alt. Frag.
Delayed-NMDQ
Dist_L; Dense_L
Student # 19
Alternative with Sci. Frag.
Delayed-NMDQ
Dist_L; Move_S; Color_L; Uni_G; Empty_G; NoCUof_Force
Table 4.18: Students’ types of conceptual understandings three-months after the RBT.
166
Summary In summary, about 35% of the RBT students exhibited slight progress toward a scientific understanding from the pretest to the posttest, whereas 65% of the RBT students stayed in the same types of conceptual understandings that they exhibited before the instruction. Three-months after the instruction, 15% of the RBT students who made progress toward a scientific understanding reverted to their initial conceptual understandings of the PNM. Individual students in the RBT group pursued different conceptual pathways from the pretest to the post to the delayed posttest. The next section articulates each one of these conceptual pathways identified in the RBT group.
The RBT Group Students’ Conceptual Pathways of the PNM Question 2.2: How does the conceptual understanding of high school students on the aspects of the PNM change from preinstruction to post and to delayed posttest administered three-months after the RBT? A subset of the nine conceptual pathways recorded in the RBTw/MR group characterized the RBT group students learning routes of the PNM during the study. The conceptual pathways identified in the RBT group contained conceptual pathway 5, slight progress and stable; conceptual pathway 7, slight progress with full decay; and conceptual pathway 9, no progress. The majority of the RBT students’ conceptual pathways showed characteristics of the conceptual pathway 9. The following sections discuss each one of the conceptual pathways that represent the conceptual characteristics of the RBT group students. 167
Conceptual pathway 5: Slight progress and stable As shown in Table 4.19, four of the 19 RBT students (21%) exhibited slight progress from the pretest to the posttest, and then their understanding of the PNM persisted to the delayed posttest. Three of the four RBT students’ conceptual understandings (numbers 3, 4, 8) moved toward a scientific understanding with onecategory improvement in their types of conceptual understandings from the pre to the posttest (see Table 4.15, Table 4.17 and Table 4.18). However, the progression that student 12 achieved by moving from no understanding to alternative fragments category seems to be fairly weak change in her understandings of the PNM and far below the targeted conceptual understandings of scientific understanding or scientific fragments.
Pre
Post
Delayed
3
3
1
1
Scientific Sci. Frag. Sci.w/Alt.Frag Alt. w/Sci.Frag.
3
Alternative Frag. No Understanding
1
Table 4.19: Conceptual pathway 5 within the RBT group (number 3, 4, 8, 12).
The change that student 3 attained in her conceptions of the PNM was discussed as a representative of this group. Student 3 experienced challenges with almost every aspect of the PNM at least in one of the three physical states before starting the RBT 168
instruction (see Table 4.15). Her responses also included very brief, macroscopic explanations of the given phenomena on the pretest, (e.g. “when it [a solid] turns into a liquid they will melt together and take the form of the container,” [Pre-NMDQ-q8] or “after the valve is opened, the gases will mix” [Pre-NMDQ-q6]) Although student 3 indicated no understanding of perceiving matter as being discrete particles before her involvement in the RBT instruction, she provided evidence of viewing matter as being discrete particles in all three states of matter on the posttest (see Figure 4.16). However, her pictorial representation of matter at the submicroscopic scale revealed one of her alternative conceptions, the existence of rigid lines (bonds) between particles of solids and liquids. Yet the ambiguity with the origin of the alternative conception concerning the representation of rigid lines between the particles of liquids and solids became clear with her explanation during the interview. An excerpt from her post interview follows: Researcher: In question 1 on the test, you were given a piece of iron, a glass of water and an air filled balloon. You were asked to draw how you would see these materials at the small scale, if you could see them with a powerful device. What are your pictures telling us about the three states of matter? Student 3: The particles in the cube of iron are close together (SciDist_S), and they are very organized (SciArr_S), whereas in the glass of water, they are kind of little spread apart (AltDist_L) and not as quite organized (SciArr_L), but then, in the air filled balloon, they are kind of spreading around randomly and far apart from each other (SciArr_Dist_G). Researcher: Pointing to the solid lines between the particles of a solid and a liquid, what do these solid lines between the particles represent? Student 3: Hmm… I am not really sure. Researcher: What made you draw these lines between the particles? Student 3: I just remember from the pictures we saw. I do not remember what they represent, but remember seeing the lines. Researcher: Where did you see the pictures? Student 3: In our book [refers to their science book]. 169
Student 3’s interview responses indicated that, her explanation of matter in the three physical states was limited to the arrangement of and the distances between the particles. She offered no explanation about the other aspects of the PNM. As she mentioned during the interview, it is possible to see solid lines between the particles in some cases in the chemistry/physical science textbooks. To represent the crystal lattice structure of the ionic compounds, (e.g., NaCl, Table salt) the ball-and-stick models are frequently shown in the chemistry textbooks (see Figure 4.17). No sticks actually exist between the particles; however, the attraction forces keep the particles of matter together.
Posttest (NMDQ-q1) (SciPart_S_L_G, AltBond_S_L)
Figure 4.16: Drawings that represent student 3’s conceptions of the discrete nature of matter in the three physical states on the posttest.
Figure 4.17: The crystal lattice structure of the salt (Tocci & Viehland, 1996, p.159).
170
The following excerpt from the same post-interview provides a more complete picture of her understanding of the PNM. Student 3 held an understanding of some aspects of the PNM, but she needed to be probed about certain ideas. However, she was not able to connect all those ideas together spontaneously. Her conceptions of the PNM appeared to exist as being discrete facts in her explanatory framework rather than being in a coherent network with obvious associations among the concepts of the PNM. Researcher: How does the behavior of solid particles change, when a solid turns into a liquid? Student 3: They may spread out a little more, but not very much, and, they are not so organized (SciArr_S_L). Researcher: How does the motion of particles change when a solid melts? Student 3: A solid, they kind of vibrate together, as a liquid they move around together (SciMove_S_L). Researcher: What keeps the particles of a solid together? Student 3: The force of attraction (SciForce_S). Researcher: How strong are those forces among the particles? Student 3: It is really strong, because it keeps them together. As a liquid it is not so strong I guess (SciForce_L). Over a three-month period, her conceptions of the PNM exhibited stability with continuation of the same scientific and nonscientific conceptions. For example, her representation of rigid lines between the particles of solids and liquids come into view again in her picture of matter at the submicroscopic scale (see Figure 4.18).
Delayed Posttest (NMDQ-q1) (SciPart_S_L_G, AltBond_S_L)
Figure 4.18: Drawings that represent student 3’s conceptions of the discrete nature of matter in the three physical states on the delayed posttest. 171
Conceptual pathway 7: Slight progress with a full decay The three students (numbers 2, 6, 10) in the RBT group exhibited slight progress in their understandings of the PNM from the pre to the posttest, but their conceptions of the PNM fully decayed within three months on the delayed posttest (see Table 4.20). Before their engagement in the RBT, these three students had difficulty with the idea of the discrete nature of matter as well as the other aspects of the PNM (see Table 4.15). After completion of the RBT instruction, their conceptual understandings of the PNM improved with the change of a small number of their alternative conceptions to a scientific understanding, but none of these students were able to completely change all of their nonscientific conceptions (see Table 4.17). Three-months after the RBT instruction, their conceptions of the PNM reverted to the original conceptual understandings that they expressed on the pretest. On the delayed posttest, these students particularly struggled with the idea of the discrete nature of matter in the three physical states just as they had before the intervention. The variation evidenced in student 6’s conceptions about the aspects of the PNM portrays the typical example of students in this group who followed this particular conceptual pathway—slight progress with a full decay. The following discussion presents his data. As seen in Figure 4.19 below, before the RBT, student 6 perceived matter as being continuous based upon the evidence that he presented in his picture (e.g., continuous scratch lines). The only aspect that he held a scientific understanding consisted of the motion of particles in the gas state (e.g., “The air is moving around (SciMove_G)” [Pre-NMDQ-q2]).
172
Pre
Post
Delayed
Scientific Sci. Frag. 3
Sci.w/Alt.Frag Alt. w/Sci.Frag.
3
3
Alternative Frag. No Understanding
Table 4.20: Conceptual pathway 7 within the RBT group (numbers 2, 6, 10).
Solid
Liquid
Gas
Solid
Pretest (NMDQ-q1) (AltPart_S_L_G)
Liquid
Gas
Posttest (NMDQ-q1) (SciPart_S_L_G; AltBond_L)
Solid
Liquid
Gas
Delayed Posttest (NMDQ-q1) (AltPart_S_L_G)
Figure 4.19: Drawings that represent student 6’s conceptions of the discrete nature of matter in the three physical states.
After the RBT instruction, even though student 6 held a scientific understanding of many aspects of the PNM, he failed to develop a scientific understanding about all eight aspects of the PNM. He believed that distances between particles of liquids are in between the distances between particles of solids and gases (see Table 4.17 and Figure 4.20). Additionally, in his representation of the arrangement of and the distances between particles of three states of matter, he showed solid lines (bonds) between the particles of solids and liquids, but not gases (see Figure 4.20). However, in the post interview, he 173
explained the reason why he sketched solid lines between particles of solids and liquids. An excerpt from his post-interview follows: Researcher: How about these solid lines between the particles a solid and a liquid (Figure 4.20)? Student 6: It is just showing that they [particles] are still connected. They are still compact. Researcher: In nature, are there lines/sticks between the particles of solids and liquids to hold them together? Student 6: No, it is just space in between the particles (SciEmpty_S_L). Researcher: How does sugar dissolve in water? Student 6: Particles (sugar) like break away from each other, and become less concentrated, and spread out through the liquid (SciUni_L). Researcher: Is there any relationship between a grain of sugar and a molecule of sugar? Student 6: Grain of sugar has its own shape, but a molecule of sugar is like kind of broken down (SciPart_S). Researcher: Suppose that two containers are connected with a valve. If these containers are filled with two different gases, what happens to the particles of gases, when we open the valve? Student 6: Particles of each gas will spread out, go through the little valve thing and mix in with the other gases. ….certain amount of one type and another amount of other type in each container (SciUni_Move_G). Researcher: Consider that you have a flask filled with a gas, the gas is cooled down until it liquefies, how does the behavior of gas particles change in this cooling process? Student 6: The gas particles slow down (SciMove_L_G), become more tightly compact to a liquid state. They are still able to move around. Researcher: You said that they become tightly compact. What keeps those particles together? Student 6: Like the attraction of energy between these particles becomes stronger. And so, they attract each other and become compact (SciForce_L_G). Researcher: What is there between the particles of matter? Student 6: Just space, nothingness (SciEmpty_G). On the delayed posttest, student 6 provided explanations concerning some aspects of the PNM, [e.g., for the given scenario of condensation of a gas, he said, “the particles calm down, move slower (SciMove_L_G), become compacted (SciDense_L) and move together” (Delayed-NMDQ-q7, see Figure 4.21)]. Yet based on the established criteria, 174
the decay in his perception of matter as discrete particles was considered as being a full decay in his overall conceptual understanding of the PNM (see Figure 4.19).
Posttest (NMDQ-q3) (SciArr_S_L_G; SciDist_S_G; AltDist_L; AltBond_S_L)
Figure 4.20: Drawings that represent student 6’s conceptions of the spacing between the particles on the posttest.
Posttest (NMDQ-q7) (SciDense_L, AltArr_L)
Figure 4.21: Drawing that represent student 6’s conception of condensation of a gas on the delayed posttest.
Conceptual pathway 9: No progress As indicated in Table 4.21, a total of twelve RBT students did not exhibit any progression toward a scientific understanding of the PNM at any point of the data collection. There were three groups of students that followed the same conceptual pathway, but held different types of conceptual understandings at the beginning of the 175
study and each group’s type of conceptual understandings persisted throughout the study. Just one group of students’ conceptual path is articulated as an example of this type of conceptual pathway. The students (numbers 5, 13, 14, 16, 18) whose type of conceptual understanding was identified as a scientific understanding with alternative fragments were able to view matter as being discrete particles before the RBT (see Table 4.15) and their overall conceptual understandings remained the same over the course of the study. However, all of them held alternative conceptions about the aspect of the relative distances between the particles of liquids on the pretest, [e.g., (see Figure 4.22), “Gas particles are spaced far apart (SciDist_G). Liquid particles are closer than in gas phase, some room to move (AltDist_L). Solid particles are closer than in water, barely room to move (SciDist_S)” (Student 14, Pre-NMDQ-q3)]. In addition, 4 of these 5 RBT students did not show any evidence of understanding the existence of attraction forces among the particles.
Pre
Post
Delayed
Sci.w/Alt.Frag
5
5
5
Alt. w/Sci.Frag.
5
5
5
Alternative Frag.
2
2
2
Scientific Sci. Frag.
No Understanding
Table 4.21: Conceptual pathway 9 within the RBT group (Sci.w/Alt.Frag, numbers 5, 13 14, 16, 18; Alt. w/Sci.Frag., numbers 7, 11, 15, 17, 19; Alternative Frag., numbers 1, 9). 176
Pretest (NMDQ-q1)
(SciPart_S_L_G) Figure 4.22: Drawings that represent student 14’s conceptions of the discrete nature of matter on the pretest.
As a typical example of this group, student 14 was able to restructure her explanatory framework with the construction of scientific understandings about a few aspects of the PNM on the posttest (see Table 4.15 and Table 4.17). As her understanding of the PNM evolved during the intervention, she also constructed an alternative conception (see Figure 4.23). Regarding her explanation of the issue with her drawing in the post-interview (see the excerpt below), she was aware of the fact that the attraction forces are very strong between particles of solids and liquids, whereas gases are free to move with negligible attraction between the particles. Thus, the developing an understanding of the existence of attraction forces between the particles with varying strength stimulated the alternative conception of considering something like sticks between particles in order to keep them together, which came out as rigid lines between the particles in her representation of the solid and liquid states at the particulate level. When she was asked to explain her picture below (see Figure 4.23), her response in the post-interview follows: Student 14: The solid, they [the particles] are orderly arranged, and I tried to make these about as many as they were in here [she points to pictures for solid and liquid], they are supposed to have the same 177
[number of particles]. So, these [solid particles] are orderly arranged and these are not [liquid particles] (SciArr_S_L). And then, the gas particles are not as close together. I put arrows to show that they are going all different directions (SciDist_Move_G). Researcher: What do these solid lines between the particles represent? Student 14: I am not sure. It just helped me organize them. It is like the attraction between the particles. Researcher: What would you say about the existence of attraction forces between the particles of matter in the three physical states? Student 14: The attraction in a solid is, I guess, there is more of it than the liquid. Gas has the very least attraction. There is not much attraction (SciForce_S_L_G). An excerpt from the same interview along with her pictorial drawings (see Figure 4.24) offer evidence for the development she experienced in her conceptual understanding of the PNM after the RBT instruction. In spite of having a structured comprehensive understanding of the PNM, the coexistence of alternative conceptions in her explanatory framework such as believing in the relative distances among the liquid particles as in between solids and gases situated her type of conceptual understanding in scientific with alternative fragments category. Her explanations in the post-interview follow: Researcher: Consider that you have a flask filled with air. If air is cooled down until it liquefies, how does the behavior of air particles change? Student 14: It would all kind of go to the bottom I guess (SciDense_L). They would attract more (SciForce_L), so they would not fill up as much space. So like, you would see the shape of it; that was formed by the shape of the container. I think it would be visible (see Figure 4.24). Researcher: How does the motion of particles change, when a gas turns into a liquid? Student 14: They move faster in the gas, and further I guess. And then, in the liquid, there is more attraction, so, they move slower and not as far (SciMove_L_G). Researcher: OK. Researcher: How does the behavior of solid particles change, when a solid turns into a liquid? 178
Student 14: They lose their arrangement and become not as orderly (SciArr_L), and spread out more (AltDist_L) (see Figure 4.24). They move faster (SciMove_L). Researcher: What keeps the particles of a solid together? Student 14: The forces of attraction. In the solid state, it is really high (SciForce_S). They [the particles] cannot move anywhere; they stay in one place and kind of vibrate (SciMove_S), but then in a liquid, they move out (SciMove_L). Researcher: Why is it easy to compress gases? Student 14: Because there is more like empty space in between the particles (SciEmpty_G). You can like push the particles closer together.
Posttest (NMDQ-q1) (SciPart_S_L_G, AltBond_S_L)
Figure 4.23: Drawings that represent student 14’s conceptions of the discrete nature of matter on the posttest.
Posttest (NMDQ-q7)
Posttest (NMDQ-q8)
(SciDense_L; AltDist_L)
(SciDense_L; AltDist_L)
Figure 4.24: Drawings that represent the student 14’s conceptions of condensation of a gas and melting of a solid on the posttest.
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On the delayed posttest, the conceptions of the PNM that student 14 on the pre and the posttest (i.e., the distances between particles of liquids) persisted, as her alternative representation of rigid lines between the particles was no longer evidenced in her explanatory framework (compare Figure 4.22, Figure 4.23 and Figure 4.25). For example, to explain the condensation of a gas, she said, “particles come closer together (SciDense_L) and form a volume. They contour to the shape of their container. The picture shows the molecules coming closer together (Student 14, Delayed-NMDQ-q7)” (see Figure 4.26). In response to the question about why particles of a solid are packed close together, she stated that “they have more force pulling together than the liquid does (SciForce_S). They can’t move far because of this pulling force (SciMove_S)” [DelayedNMDQ-q8] In describing the behavior of solid particles when they turn into a liquid, she said, “they [solid particles] speed up, because energy has been gained (SciMove_S_L). They [liquid particles] move, but not real far. They stay closer together than gas (SciDist_G, AltDist_L)” [Delayed-NMDQ-q8].
Delayed Posttest (NMDQ-q1) (SciPart_S_L_G)
Figure 4.25: Drawings that represent student 14’s conceptions of the discrete nature of matter on the delayed posttest.
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Delayed Posttest (NMDQ-q7)
Delayed Posttest (NMDQ-q8)
(SciDense_L; AltDist_L)
(SciDense_L; AltDist_L)
Figure 4.26: Drawings that represent student 14’s conceptions of condensation of a gas and melting of a solid on the delayed posttest.
Summary The RBT group students’ conceptual understandings also advanced toward a scientific understanding with the development of the scientific views of a few aspects of the PNM on the posttest. However, the change in the RBT students’ types of conceptual understandings of the PNM did not appear to be as dramatic as it was evidenced in the RBTw/MR students’ types of conceptual understandings. In this respect, the conceptual pathways pursued by the RBT group students did not show a wide range of diverse routes from the pretest to the post to the delayed posttest as was identified in the RBTw/MR group. The range for the RBT group varied between slight progress to no progress and stable to full decay. Thus far, the RBTw/MR and RBT group students’ types of conceptual understandings of the PNM in three data collection points were presented for each group. In addition, the patterns of individual students’ conceptual pathways of the PNM in each group were discussed with examplary quotes. The following section compares and contrasts the two groups of students’ conceptual understandings of the PNM within and across the groups both descriptively and statistically. 181
Comparison of the RBTw/MR and the RBT Group’s Conceptual Understandings
Based on Descriptive Analysis Question 3a.1: How do high school students’ types of conceptual understandings of the PNM differ immediately after and three-months after completion of the RBTw/MR instruction? Table 4.22 summarizes the frequency counts of the RBTw/MR and the RBT group students’ types of conceptual understandings from the pre to the post to the delayed posttest. On the pretest, none of the students in either group held the targeted conceptual understandings of scientific and scientific fragments. The majority of the students in both groups (82.6% RBTw/MR and 73.7% RBT) consistently exhibited nonscientific types of conceptual understandings, including: alternative with scientific fragments, alternative fragments or no understanding. Immediately after the instruction, almost all of the RBTw/MR students (91.3%) showed at least one-category progression toward a scientific understanding. More specifically, 52.1% of the RBTw/MR students held the types of conceptual understandings of either scientific or scientific fragments by exhibiting either radical or moderate progress. While 34.8% of the RBTw/MR group students held onto their scientific types of conceptual understandings of the PNM on the delayed posttest, 17.4% of the RBTw/MR students who previously held a scientific understanding of the aspects of PNM on the posttest regressed to the less scientific understanding categories of conceptual understandings such as scientific with alternative fragments.
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Type of Conceptual Understandings Scientific Sci. Frag. Sci.w/Alt.Frag. Alt.w/Sci.Frag. Alternative Frag. No Understanding Total
Pretest
Posttest
Delayed Posttest
RBTw/MR
RBT
RBTw/MR
RBT
RBTw/MR
RBT
0 (0%) 0 (0%) 4 (17.4%) 17 (74%) 1 (4.3%) 1 (4.3%)
0 (0%) 0 (0%) 5 (26.3%) 11 (57.9%) 2 (10.5%) 1 (5.3%)
11 (47.8%) 1 (4.3%) 8 (34.8%) 3 (13.1 %) 0 (0%) 0 (0%)
0 (0%) 0 (0%) 11 (57.9%) 5 (26.3%) 3 (15.8%) 0 (0%)
7 (30.4%) 1 (4.3%) 10 (43.6%) 4 (17.4%) 1 (4.3%) 0 (0%)
0 (0%) 0 (0%) 8 (42.1%) 8 (42.1%) 3 (15.8%) 0 (0%)
23 (100%)
19 (100%)
23 (100%)
19 (100%)
23 (100%)
19 (100%)
Table 4.22: Summary of the RBTw/MR and the RBT group students’ types of conceptual understandings of the PNM.
Figure 4.27 graphically illustrates the changes observed in the RBTw/MR group students’ conceptual pathways of the PNM over time. The columns of 1, 3, 5, and 7 from left to right in the figure demonstrate how many of the RBTw/MR students experienced what type of changes in their conceptual understandings of the PNM between the pre and posttest. The consecutive columns, those of which stand next to the columns of 1, 3, 5, and 7, represent the same number of the RBTw/MR students as the preceding columns but illustrate the conceptual routes that these students pursued between the post and delayed posttest. As shown in Figure 4.27, seven of the 23 RBTw/MR students (30.4%) exhibited radical progress in their conceptual understandings of the PNM with at least three183
category progression toward a scientific understanding from the pretest to the posttest. Four of these 7 RBTw/MR students then reverted to the less scientific understandings by demonstrating a slight or moderate decay in their conceptual understandings of the PNM on the delayed posttest. Moreover, 5 of the 23 RBTw/MR students (21.7%) demonstrated moderate progress by achieving two-category improvement in their conceptual understandings on the posttest. One of these 5 RBTw/MR student’s conceptual understanding of the PNM fully decayed, whereas the remaining 4 RBTw/MR students persisted in their conceptual understandings over a three-month period on the delayed posttest.
9
8
7
6
Number of Students
5
4
3
2
1
0
Pre-Post
Post- Pre-Post Delay
Post- Pre-Post Delay
PostDelay
Pre-Post
Radical Progress or Stable
Moderate Progress or Stable
Slight Progress or Stable
Slight Decay
Moderate Decay
Full Decay
PostDelay No Progress
Figure 4.27: The overall trends in the RBTw/MR group students’ conceptual pathways of the PNM. 184
Slight progress was identified in 9 of the 23 RBTw/MR students’ (39.1%) conceptual understandings. These students showed one-category progression toward a scientific understanding of the PNM on the posttest. Then, 3 of the 9 RBTw/MR students indicated either a slight or full decay, as 6 of these 9 RBTw/MR students maintained the types of conceptual understandings that they held after the RBTw/MR instruction. Additionally, 2 of the 23 (8.7%) RBTw/MR students demonstrated no progress from the pretest to the posttest. While one of these 2 RBTw/MR students showed one-category progression in his type of conceptual understanding on the delayed posttest, the other student continued to hold the same type of conceptual understanding, indicating no progress throughout the study.
Question 3a.2: How do high school students’ types of conceptual understandings of the PNM differ immediately after and three-months after completion of the RBT? None of the RBT student’s conceptual understandings met the criteria of the targeted conceptual understandings of scientific or scientific fragments. Nevertheless, 57.9% of the RBT students held conceptual understanding of scientific with alternative fragments after the instruction. Only 31.6% of the RBT students indicated slight progress in their conceptual understandings by moving from the conceptual understanding category of alternative with scientific fragments to scientific with alternative fragments. Three-months after the instruction, 15.8% of the RBT students’ conceptual understandings of the PNM differed from their initial types of conceptual understandings by meeting the criteria of scientific with alternative fragments category. Moreover, 15.8% of the RBT students who held the conceptual understanding of scientific with alternative 185
fragments on the posttest regressed to the alternative with scientific fragments category on the delayed posttest. Figure 4.28 shows the graphical illustration of the changes taken place in the RBT group students’ conceptual pathways of the PNM from the pretest to the post to the delayed posttest. The four columns on left side of the Figure 4.28 stand for the conceptual changes of radical and moderate progress between the pre, post and the post, delayed posttest. However, no student in the RBT group attained either radical or moderate progress toward a scientific understanding in their conceptual understandings of the PNM during the course of the study.
12
10
Number of students
8
6
4
2
0
Pre-Post
PostDelay
Pre-Post
Post- Pre-Post Delay
Post- Pre-Post Delay
Radical Progress and Stable
Moderate Progress and Stable
Slight Progress and Stable
Slight Decay
Moderate Decay
Full Decay
PostDelay No Progress
Figure 4.28: The overall trends in the RBT group Students’ Conceptual Pathways of the PNM. 186
The portrait of identified patterns in the RBT students’ conceptual pathways substantially deviated from the patterns observed in the RBTw/MR students’ conceptual pathways. Seven of the 19 RBT students (36.84%) displayed slight progress with onecategory enhancement in their conceptual understandings of the PNM. However, 3 of these 7 RBT students’ conceptual understandings fully decayed on the delayed posttest, while 4 of the 7 RBT students’ conceptual understandings indicated persistence threemonths after the RBT instruction. Moreover, 12 of the 19 RBT students (63.15%) continued to hold the same type of conceptual understandings of scientific with alternative fragments, alternative with scientific fragments or alternative fragments from the pre to the post to the delayed posttest without indicating any progression in their type of conceptual understandings.
Question 4a: How do the two groups compare just before, immediately after, and three-months after completion of the RBTw/MR and the RBT instruction? It should be noted that a majority of the students in both groups (RBTw/MR, 82.6%; RBT, 73.7%) entered either one of the interventions with the types of conceptual understandings that dominantly consisted of nonscientific conceptions of the PNM such as alternative understanding with scientific fragments, alternative fragments, and no understanding. Immediately after the instruction, the growth in the RBTw/MR students’ conceptual understandings of the PNM ranged from no progress to radical progress, whereas the RBT students only showed slight progress toward a scientific understanding of the PNM. Over a three month period, although the patterns in the durability of both groups of students’ conceptual understandings of the PNM changed between stable and 187
full decay, the RBTw/MR group students were more likely to hold onto their scientific understandings of the PNM. Based on Statistical Analysis This section statistically makes sense of the data. To assess the effectiveness of the two different types of instruction, the RBTw/MR students’ conceptual understandings of the PNM were statistically compared with the RBT students’ conceptual understandings. Students’ conceptual understandings of the PNM were identified by their responses to the open-ended questionnaire called the Nature of Matter-Diagnostic Questions (NMDQ). The researcher developed a coding scheme to facilitate the scoring of students’ performance as to understanding the aspects of the PNM before, immediately after, and three-months after the RBTw/MR and the RBT instruction (see Chapter 3). On the pretest, students’ conceptual understandings were measured on a scale of 0 to 22. On the post and the delayed posttest, students’ conceptual understanding scores varied between 0 and 34. The range of scale was greater on the posttest and delayed posttest, because students were asked not only to verbally explain the given tasks, but also to draw particle models to show their understandings pictorially (see Chapter 3). On these two measuring scales, the higher the scores students achieved, the more comprehensive scientific understanding they held about the PNM. These scores were utilized to make statistical comparisons between the groups. Because the scales were not equivalent to assess students’ written responses on the pre and the posttest, the numerical data for the pre and the posttest were not appropriate for conducting the statistical procedures to explore differences, if any, within each group. For that reason, students’ types of conceptual understandings of the PNM identified through qualitative coding for each data 188
collection point were transferred into numerical values ranging from 0 to 5 to be used for repeated measures analysis within each group (see Chapter 3). Question 3b.1&2: How do high school students’ types of conceptual understandings of the PNM differ immediately after completion of the RBTw/MR and the RBT instruction? The Sign Test was performed for each group to determine if there was a significant difference in each group of students’ conceptual understandings of the PNM between the pretest and the posttest. Table 4.23 presents the Sign Test statistics and positive, negative and no change cases for both groups. Twenty one of the 23 RBTw/MR students moved toward a scientific understanding after completion of the instruction, and just 2 of the 23 RBTw/MR students recorded no change between the two data collection points. The Sign Test analysis revealed a statistically significant median difference (Mpre=2; Mpost=4, p0.05) in favor of either of the two groups. This result indicated that both groups of students’ conceptual understandings of the PNM were similar before they started the RBTw/MR and the RBT instruction. Moreover, compared to the maximum likely score of 22 on the pretest, the median score of 10 was found for each group of students on the pretest.
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The frequencies and percentages of students’ types of conceptual understandings of the PNM were consistent with the findings of previous studies (Haidar & Abraham, 1991; Johnson, 1998c; Kabapinar et al., 2004). In Johnson’s (1998) study, 45% of the students held the nonscientific models of matter before instruction. These students either perceived matter as continuous or accepted the raisin cake model in which particles are considered to be embedded in continuous matter. The remaining 55% of the students in the same study viewed matter as being made of discrete particles with each particle demonstrating macroscopic properties. Although this particle model was closer to a scientific view of the PNM, these students did not express a fully scientific view either. Haidar and Abraham (1991) found that on average, 73.73% of students who were specifically probed about the particle ideas failed to provide scientific responses in the contexts of dissolution, diffusion, effusion, and states of matter. Therefore, these students’ conceptions met the criteria established for the categories of no understanding or an alternative understanding. Kabapinar et al. (2004) also reported that on the pretest, about 90% of the students in both experimental and control groups of the study did not refer to the particle ideas at all while explaining the processes of dissolution of sugar in water. Additionally, in Singer et al.’s study, the middle school students scored low on the pretest with the average mean score of 1.63 out of 5. In summary, as reported in other studies, students in this study consistently showed fragments of nonscientific conceptions of the PNM and their conceptual understandings concerning the aspects of the PNM were considered to be nonscientific or incoherent before their engagement in any of the instructional interventions.
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Assertion 2: Even though both groups of students made progress toward a scientific understanding after their involvement in the two different instructions, the RBTw/MR group students developed more scientific conceptual understandings of the PNM than the RBT group students. Immediately after the instruction, 52.1% of the RBTw/MR group students progressed toward the targeted conceptual understandings of scientific and scientific fragments. Additionally, 34.8% of the students’ conceptual understandings were identified to be scientific understanding with alternative fragments. Only 13% of the students’ conceptual understandings persistently showed the components of the alternative conceptions in many aspects of the PNM and met the criteria set for the category of alternative understanding with scientific fragments. In the RBT group, no students’ conceptual understandings met the criteria established for the categories of targeted conceptual understandings of scientific or scientific fragments. The most satisfactory scientific type of conceptual understanding achieved by these students was scientific understanding with alternative fragments. In the RBT group, 57.9% of the students’ conceptual understandings were classified into this category. However, 42.1% of the RBT students exhibited either no understanding, alternative fragments or alternative with scientific fragments as their type of conceptual understanding, which were not as desirable types of conceptual understandings as scientific and scientific fragments. The Sign Test revealed a statistically significant difference (p
