Investigating Community Food WEBS: The Ecological Importance of Spiders Dustin J. Wilgers Department of Natural Sciences, McPherson College Overview This hands-‐‑on activity investigates food webs through focusing on a key predator in many communities, spiders. By building their own webs, students not only learn about how spider webs function, but also how web design may affect capture efficiency by using the scientific method. Students will gain an appreciation for the benefits that spiders provide humans, including food production and disease control, through their role in the ecological communities. Learning Objectives From this activity, students will gain a better understanding of: -‐‑the organization of biological communities with regards to food-‐‑based interactions -‐‑food web construction and organization -‐‑the importance of spiders to the stability of their communities and to humans -‐‑engineering solutions to complex problems -‐‑how the scientific method works Introduction Biological communities are a collection of interacting species in a given area. One of the most important interactions that these species engage in involves the transfer of energy from one individual to another, consumption (i.e. herbivory, predator-‐‑prey). Tracking the transfer of energy throughout this collection of species is one extremely important method to understand how communities are organized, and they even allow us to identify species that are important for community stability. Food-‐‑web diagrams are one way to represent the structure and interactions in a community or subset of a community (Figure 1). Food webs are organized into similar groups based on where organisms get their energy called trophic levels. Plants are considered producers because of their ability to convert sunlight energy into usable energy (food) through the process of photosynthesis. All other organisms are considered consumers, as they must eat their food by consuming other organisms (dead or alive; plant, fungi, or animal). Herbivores are animals that eat only plants, while predators eat only other animals. Classroom Questions (Depending on age-‐‑level and time, these questions can be done as a group or assigned as homework, there are blank food webs at the back) 1. Name the consumers in the diagram? Name the producers? Consumers: Caterpillar, Grasshopper, Beetle, Spider, Bird Producers: Corn, Tree, Grass 2. What is different between the animals found in the middle row, compared to the animals found on the top row? What are the names for these groups of consumers? The animals found in the middle row only consume plants; these animals are called herbivores. The animals on the top row mostly consume other animals (except birds, which are a great example of another generalist consumer); these animals are called predators.
3. What do the arrows on the diagram represent? The arrows represent interactions between organisms, specifically consumption. The arrow is pointing toward the organisms being eaten. This means the arrows also represent a transfer of energy from one organism to another.
4. Why aren’t any arrows pointing from the plants? What do they eat? Where do they get their energy? Plants don’t consume anything in that food web. Plants make their own food through photosynthesis using energy from the sun, not other organisms. If there were a sun at the base of the food web, then all the producers would have arrows pointing toward it.
5. Optional: Have students draw their own arrows between the organisms to make their own food web, then label each organism as a producer, predator, or herbivore.
Predators
Consumers
Herbivores
Producers
Figure 1. An example food-‐‑web diagram representing some of the interactions that commonly occur in various Kansas biological communities. The animals in this diagram are general representations of that group (e.g. all birds, not just a meadowlark) and what they could eat. Several blank versions of this diagram are in Appendix 1, in case you want to have your students work this as part of the optional activities just below. Spiders are obligate predators, meaning they must obtain the energy needed to sustain life by eating other animals. Spiders can prey on a variety of organisms, including other spiders, vertebrates (rarely), and their most common prey type, insects. It is estimated that one spider can eat as many as 2000 insects in one year (Walker 2010). As generalist consumers, many spiders play an important role in each of the communities they are found in by regulating the density of organisms across multiple trophic levels (herbivores and
predators). When you combine their variety of food types and their sheer abundance, spiders are one of the most important invertebrate predators in many ecosystems. It is clear that spiders have important ecological roles in maintaining a healthy and stable community. Spiders also directly benefit humans by consuming prey items that are pests to humans and thus reducing their abundance. Many of the insects that spiders eat are directly affect humans, including mosquitoes, a pest that transmits deadly diseases like West Nile virus, malaria, dengue and yellow fever. While many spiders eat mosquitos that fly into their web (Figure 2), two species of jumping spiders, Evarcha culicivora and Paracyrba wanlessi, are known as “mosquito terminators.” Both of these species are specialist predators, each preferring to eat mosquitoes from different life stages (adult & nymph respectively; Jackson & Cross 2015). Regardless of how mosquitoes are consumed, spiders that have this pest as a part of their diet directly reduce numbers of these pests and have the potential to reduce the spread of disease.
Figure 2. Mosquito in Web (Frank Starmer) There is an ancient proverb: “The enemy of my enemy is my friend.” Agricultural pests directly reduce crop yields by feeding on the plants, robbing their fruit/seed output that we harvest for food. Spiders indirectly benefit humans by eating of a variety of pests, including aphids, grasshoppers, leafhoppers, beetles, caterpillars (Maloney et al. 2003). Reductions in pest abundance have led to decreased crop damage (Reichert & Bishop 1990), which could help increase yields. Sadly, farmers spend billions of dollars on non-‐‑natural pesticides designed to reduce weeds and insect pests that have been shown to reduce the abundance of spiders in fields, a natural and thus environmentally friendly form of pest control (Maloney et al. 2003, Haughton et al. 1999, Thomas & Jepson 1997), and could end up resulting in a pest resurgence (Tanaka et al. 2000). Classroom Questions (Depending on age-‐‑level and time, these questions can be done as a group or assigned as homework, there are blank food webs at the back) 1. Which of the groups of organisms is more harmful to farmers (a farmer’s enemy)? Why? All of the herbivores are potentially harmful to a farmer and his crops. By consuming plant material, this could reduce the amount of grain or fruit (yield) a farmer gets from his field. 2. Which groups of organisms are enemies to the group you just identified? The predator groups (spiders and birds) are enemies of the herbivores, since they consume them.
3. If each insect herbivore eats two cobs of corn, and each spider eats five insects, how many cobs of corn does one spider save humans if they are allowed to live in crop fields? In this situation, one spider could save 10 cobs of corn by eating the insect herbivores that live in the crop fields. 4. Explain why conserving spiders actually helps humans instead of potentially hurting them. If we conserve spiders, they help us naturally because of their place in their community’s food web. Because spiders are predators on insects and other herbivores and not predators of humans or their crops, by consuming the organisms that are pests to us, spiders actually help us. We see are reduced number of pests, like mosquitos and other herbivores that may be consuming our crops and hurting our fields.
Spiders capture their prey in many different ways. Many spiders actively hunt for their food, including two of the more recognizable families wolf spiders (Lycosidae) and jumping spiders (Salticidae). Other spiders construct webs from the silk they make (all spiders make silk). These webs take on a variety of shapes and sizes (Figure 3), but all have one goal, to help catch prey. Some webs are sticky, while others help the spider detect (through vibrations) when prey items walk across their web. This adaptation helps spiders catch a variety of insects, flying and ground dwelling, more efficiently.
Cob
Sheet
Funnel
Orb
Figure 3. Some of the basic web types that spiders construct with silk in order to capture their food. Each type represents the typical structure, but these can vary considerably in shape size and pattern depending on the species of spider that spins it. In this activity, students get to design and construct their own webs, test how effective they are at removing pests, and then see how the removal of pests affects crop yield. From this, students will hopefully gain an appreciation of the ecological importance of spiders to their ecosystem and humans, especially in the Midwest, where agriculture is a big part of our economy). Useful Terms Community – a group of potentially interacting species in a given area Food web – a diagram representing consumer interactions that occur in a community Predator – an animal that naturally eats other animals as food for its energy needs
Generalist – an organism that consumes a variety of different prey types Ecosystem – a biological community of organisms and their physical environment Trophic Levels – groups of organisms in a community that share the same function in the food chain by consuming their energy from the same group or level of organisms in their community Consumers – organisms that must get their energy by consuming another organism Producers – organisms that can get their energy from the sun Photosynthesis – the process that plants use to convert sunlight energy into food energy Specialist – an organism that consumes only a very specific food type Adaptation – a trait that has evolved to increase an organism’s ability to survive and/or reproduce in their environment Intended Age Range: K-‐‑8 (See below for NGSS Core Ideas Addressed) Group Activity Depending on the grade level, you can adjust this activity to meet several outcomes. -‐‑Younger grade levels-‐‑ Simply create a “typical” spider web by following the directions below. Afterwards, each student can test how good these webs are at catching prey items. This artistic activity will engage students with a really important spider trait that helps them catch prey and will also reinforce the importance of spiders to their ecosystem and humans. -‐‑Older grade levels-‐‑ Challenge the students to “Design a Better Web” that is more efficient spider web at catching prey with a limited amount of “silk”. This engineering style problem introduces a variety of engineering skills, such as creativity, product design, and testing, while also introducing aspects of the scientific method, such as producing hypotheses, collecting data to test hypotheses, and forming conclusions (Appendix 2). Activity Supplies Paper Plates (1 / student) Silk = Knitting Yarn (1 roll, any color) Tape Scissors (enough to share between students) Paper hole punch Ping-‐‑pong balls (6 pack) Self-‐‑stick Velcro (dots or thin strips; 1 package) – hint: strips work better Candy corn or Popcorn (prize) Create a Typical Spider Web and Test Its Effectiveness Create a spider orb web using a paper plate and yarn (your “silk”) by following the directions below. 1) Make six ½-‐‑inch cuts equally spaced around the outside of a paper plate. These cuts will hold the “spokes” of the spider web. 2) Cut three pieces of “silk” into ~ 12 inch-‐‑long strips. Stretch one strand at a time between two of the cuts on the outside of the plate that are opposite each other, and tape the ends of the silk on the backside of the plate. Do this for all three strands so that all the cuts have a string through them. These are the “radial spokes” of the spider web. You should have something that looks like an asterisk.
3) To make the spiral catching threads of the web, start by punching a hole in the plate directly behind one of the spokes toward the center. Run one end of a longer strand of silk through that hole and tape the end of the strand to the back of the plate. Work your way around the circle, slowly making your way toward the outside of the plate, wrapping the strand once around each spoke as you go, forming a hexagon. Once you reach the outside of the web, run the other end of the strand through the another hole punched next to a radial spoke. 4) Tape the end of the circling strand to the backside of the plate once you have adjusted the tightness and placement of the crossbars.
Figure 4. A finished paper plate spider web.
Design a Spider Web Option -‐‑Using the basic principles above, students can create an endless variety of web designs. Challenge them to come up with a web that is the best at catching prey. In order to keep the challenge fair, you must standardize several features. 1) There must be at least 4 anchor points to the outside of the plate (step 2 above) 2) All students will be limited to 60” of silk 3) All silk strands must be connected (looped or taped) to another stand on at least one end Catching Prey with the Webs Place either thin strips of Velcro or Velcro dots onto Ping-‐‑Pong balls so that the Velcro is evenly spaced around the ball. You may draw insect designs on the Ping-‐‑Pong balls for added fun. These Ping-‐‑Pong balls will be your “agricultural pests.” (Figure 5). 1) Have each student stand four feet away from their web and gently toss five prey items at their web. 2) For each prey item that gets caught in their web (Figure 5), the student receives a prize of three candy corn*. *Any candy or snack will work as a prize; we chose candy corn because it represents a crop that is normally harvested and affected by agricultural pests, but popcorn works too! Make sure to point out that more prey captured by spider webs results in a larger “harvest.”
Figure 5. A prey item ping-‐‑pong ball, and one caught in a spider web. Design a Better Spider Web Challenge students to design a spider web that is better at catching prey, given a limited amount of “silk” for constructing the web. Students can use this spider web design worksheet to sketch out and evaluate their design. Using the web-‐‑making and prey-‐‑capture protocols above, students can create and test an endless variety of web designs. Encourage them to use the webs of real spiders for inspiration by searching for different spider web designs on the Internet (great resource on spider web construction: http://www.spiderzrule.com/spiderweb.htm). Next, challenge them to come up with a web that is the best at catching prey. In order to keep the challenge fair, you must standardize several features. 1) There must be at least four silk anchor points to the outside of the plate
2) All students will be limited to 60 inches of silk 3) Every silk strand must be connected (looped or taped) to another strand on at least one end
Have students collect “data” on how effective their web was at protecting crops, using the catching prey game rules above. Record their data and observation in the worksheet below in the appendix. Compare students’ data for different web designs and make conclusions on the most effective web design. Suggested Discussion Topics with Class After Activity (Can assign these as homework) 1) What does the candy corn prize represent? Why did you receive more candy corn for every insect caught in the spider web? What real life interaction and processes does this represent? The candy corn represents one of the many grains, fruits, or vegetables that farmers harvest from their fields. Through predation, spiders reduce the number of insect pests in a farm field, which will reduce herbivory and crop damage from pests and increase crop yield. 2) When farmers spray insecticide on fields to kill insect pests, spiders also decrease in abundance. How does this affect the community’s natural way of controlling the numbers of insect pests? If you could design a better insecticide, what kind of insecticide would be most effective at controlling pest populations? By spraying artificial insecticides to control pest populations, this reduces the natural control of these insect populations by also removing their predators. A better insecticide or pest control would be one that reduces insects while not affecting spider populations. 3) Where would you normally find spider webs at in a crop field? What kinds of insects do these webs typically catch? What kinds of insects would be captured if the web was turned more horizontal, or was found directly on the ground? The spider webs from this activity are typically vertical webs found above the ground between plants. These kinds of webs are very good at capturing flying insects. Horizontal webs would capture slightly different prey, maybe insects flying off the ground, while webs on the ground would be effective at catching ground dwelling insects that very rarely fly. 4) For the spider web design option. What spider web design was most effective? What features of the web do you think made it so great at catching “prey.” Are these features found in natural spider webs? If not, why do think this is the case? The answers to this question will depend on the webs that are constructed by your students. Literature Cited Haughton, A. J., Bell, J. R., and Boatman, N. D. 1999. The effects of different rates of the herbicide glyphosate on spiders in arable field margins. The Journal of Arachnology 27:249-‐‑254. Jackson. R. R., & Cross, F. R. 2015. Mosquito-‐‑terminator spiders and the meaning of predatory specialization. Journal of Arachnology 43:123-‐‑142.
Maloney, D., Drummond, F. A., and Alford, R. 2003. Spider predation in agroecosystems: Can spiders effectively control pest populations? Maine Agricultural and Forest Experiment Station Technical Bulletin: 190. Tanaka, K., Endo, S., and Kazano, H. 2000. Toxicity of insecticides to predators of rice planthoppers: Spiders, the mired bug and the dryinid wasp. Applied Entomology 35:177-‐‑187. Vollrath, F., and Selden, P. 2007. The role of behavior in the evolution of spiders, silks, and webs. Annual Review of Ecology, Evolution, and Systematics 38:819-‐‑846. Walker, C. 2010. Spider sense: fast facts on extreme arachnids. National Geographic News. October 28, 2010. Accessed July 14, 2015. http://news.nationalgeographic.com/news/2004/06/0623_040623_spiderfacts.htm l Credits Thanks to Ariel Zych and the editors at Science Friday (http://www.sciencefriday.com/) for comments and help improving this activity. The activity is free of charge to all educators. The Kansas Department of Wildlife, Parks and Tourism provided financial support for the development of this activity through the Chickadee Checkoff small grant program dedicated to nongame wildlife conservation. All I ask is that you please give me credit for the developing the activity and if possible, please let me know if you have used it and how it went via email (
[email protected]). Please feel free to provide any feedback on these activities so they can be modified/improved for future users. Kansas NGSS Science Disciplinary Core Ideas Addressed by this Activity Kindergarten K-‐‑LS1.C: Life Science – Organization for Matter and Energy Flow in Organisms -‐‑ All animals need food in order to live and grow. They obtain their food from plants or from other animals. Plants need water and light to live and grow. (K-‐‑LS1-‐‑1) -‐‑K-‐‑ESS2.C: Earth’s Systems -‐‑ Human Impacts on Earth Systems -‐‑ Things that people do to live comfortably can affect the world around them. But they can make choices that reduce their impacts on the land, water, air, and other living things. (secondary to K-‐‑ESS2-‐‑2) -‐‑K-‐‑ESS3.A: Earth and Human Activities – Natural Resources -‐‑ Living things need water, air, and resources from the land, and they live in places that have the things they need. Humans use natural resources for everything they do. (K-‐‑ESS3-‐‑1 -‐‑K-‐‑ETS1.A: Defining and Delimiting an Engineering Problem -‐‑ Asking questions, making observations, and gathering information are helpful in thinking about problems. (secondary to K-‐‑ESS3-‐‑2) -‐‑K-‐‑ETS1.B: Developing Possible Solutions -‐‑Designs can be conveyed through sketches, drawings, or physical models. These representations are useful in communicating ideas for a problem’s solutions to other people. (secondary to K-‐‑ESS3-‐‑3) 1st Grade
2nd Grade -‐‑2-‐‑LS4.D: Life Science – Biological Evolution: Biodiversity and Humans -‐‑There are many different kinds of living things in any area, and they exist in different places on land and in water. (2-‐‑LS4-‐‑1) -‐‑2-‐‑ETS1.A: Designing and Delimiting Engineering Problems -‐‑A situation that people want to change or create can be approached as a problem to be solved through engineering. (K-‐‑2-‐‑ETS1-‐‑1) -‐‑Asking questions, making observations, and gathering information are helpful in thinking about problems. (K-‐‑2-‐‑ETS1-‐‑1) -‐‑Before beginning to design a solution, it is important to clearly understand the problem. (K-‐‑2-‐‑ETS1-‐‑1) -‐‑K-‐‑ETS1.B: Developing Possible Solutions -‐‑Designs can be conveyed through sketches, drawings, or physical models. These representations are useful in communicating ideas for a problem’s solutions to other people. (secondary to K-‐‑ESS3-‐‑3) -‐‑K-‐‑ETS1.C: Optimizing the Design Solution -‐‑Because there is always more than one possible solution to a problem, it is useful to compare and test designs. (K-‐‑2-‐‑ETS1-‐‑3) 3rd Grade -‐‑3-‐‑LS2.C: Life Science – Ecosystem Dynamics, Functioning, and Resilience -‐‑When the environment changes in ways that affect a place’s physical characteristics, temperature, or availability of resources, some organisms survive and reproduce, others move to new locations, yet others move into the transformed environment, and some die. (secondary to 3-‐‑LS4-‐‑4) -‐‑3-‐‑LS4.C: Life Science – Adaptation -‐‑For any particular environment, some kinds of organisms survive well, some survive less well, and some cannot survive at all. (3-‐‑LS4-‐‑3) -‐‑3-‐‑LS4.D: Life Science – Biodiversity and Humans -‐‑Populations live in a variety of habitats, and change in those habitats affects the organisms living there. (3-‐‑LS4-‐‑4) 4th Grade -‐‑4-‐‑LS1.A: Life Science – Structure and Function -‐‑Plants and animals have both internal and external structures that serve various functions in growth, survival, behavior, and reproduction. (4-‐‑LS1-‐‑1) 5th Grade -‐‑5-‐‑PS3.D: Physical Science -‐‑ Energy in Chemical Processes and Everyday Life -‐‑The energy released [from] food was once energy from the sun that was captured by plants in the chemical process that forms plant matter (from air and water). (5-‐‑PS3-‐‑1) -‐‑5-‐‑LS1.C: Life Science – Organization for Matter and Energy Flow in Organisms -‐‑Food provides animals with the materials they need for body repair and growth and the energy they need to maintain body warmth and for motion. (secondary to 5-‐‑PS3-‐‑1) -‐‑5-‐‑LS2.A: Life Science -‐‑ Interdependent Relationships in Ecosystems -‐‑The food of almost any kind of animal can be traced back to plants. Organisms are related in food webs in which some animals eat plants for food and other animals eat the animals that eat plants. Some organisms, such as fungi and bacteria, break down dead organisms (both plants or plants parts and animals) and therefore operate as “decomposers.” Decomposition eventually restores (recycles) some materials back to the soil. Organisms can survive only in
environments in which their particular needs are met. A healthy ecosystem is one in which multiple species of different types are each able to meet their needs in a relatively stable web of life. Newly introduced species can damage the balance of an ecosystem. (5-‐‑LS2-‐‑1) -‐‑5-‐‑ESS3.C: Earth Systems – Human Impacts on Earth Systems -‐‑Human activities in agriculture, industry, and everyday life have had major effects on the land, vegetation, streams, ocean, air, and even outer space. But individuals and communities are doing things to help protect Earth’s resources and environments. (5-‐‑ESS3-‐‑1) -‐‑5-‐‑ETS1.A: Engineering Design – Defining and Delimiting Engineering Problems -‐‑Possible solutions to a problem are limited by available materials and resources (constraints). The success of a designed solution is determined by considering the desired features of a solution (criteria). Different proposals for solutions can be compared on the basis of how well each one meets the specified criteria for success or how well each takes the constraints into account. (3-‐‑5-‐‑ETS1-‐‑1) -‐‑5-‐‑ETS1.B: Engineering Design – Developing Possible Solutions -‐‑Research on a problem should be carried out before beginning to design a solution. Testing a solution involves investigating how well it performs under a range of likely conditions. (3-‐‑ 5-‐‑ETS1-‐‑2) -‐‑At whatever stage, communicating with peers about proposed solutions is an important part of the design process, and shared ideas can lead to improved designs. (3-‐‑5-‐‑ETS1-‐‑2) -‐‑5-‐‑ETS1.C: Engineering Design – Optimizing the Design Solution -‐‑Different solutions need to be tested in order to determine which of them best solves the problem, given the criteria and the constraints. (3-‐‑5-‐‑ETS1-‐‑3) Middle School -‐‑MS-‐‑LS1.C: Life Science – Organization for Matter and Energy Flow in Organisms -‐‑Plants, algae (including phytoplankton), and many microorganisms use the energy from light to make sugars (food) from carbon dioxide from the atmosphere and water through the process of photosynthesis, which also releases oxygen. These sugars can be used immediately or stored for growth or later use. (MS-‐‑LS1-‐‑ 6) -‐‑Within individual organisms, food moves through a series of chemical reactions in which it is broken down and rearranged to form new molecules, to support growth, or to release energy. (MS-‐‑LS1-‐‑7) -‐‑MS-‐‑LS2.A: Life Science – Interdependent Relationships in Ecosystems -‐‑Organisms, and populations of organisms, are dependent on their environmental interactions both with other living things and with nonliving factors. (MS-‐‑LS2-‐‑1) -‐‑In any ecosystem, organisms and populations with similar requirements for food, water, oxygen, or other resources may compete with each other for limited resources, access to which consequently constrains their growth and reproduction. (MS-‐‑LS2-‐‑ 1) -‐‑Similarly, predatory interactions may reduce the number of organisms or eliminate whole populations of organisms. Mutually beneficial interactions, in contrast, may become so interdependent that each organism requires the other for survival. Although the species involved in these competitive, predatory, and mutually beneficial interactions vary across ecosystems, the patterns of interactions of organisms with their environments, both living and nonliving, are shared. (MS-‐‑LS2-‐‑2) -‐‑MS-‐‑LS2.B: Life Science – Cycle of Matter and Energy Transfer in Ecosystems -‐‑Food webs are models that demonstrate how matter and energy is transferred between producers, consumers, and decomposers as the three groups interact within an ecosystem. Transfers of matter into and out of the physical environment occur at every level. Decomposers recycle nutrients from dead plant or animal matter back to the soil in terrestrial environments or to the water in aquatic environments. The atoms that make up
the organisms in an ecosystem are cycled repeatedly between the living and nonliving parts of the ecosystem. (MS-‐‑LS2-‐‑3) -‐‑MS-‐‑LS2.C: Life Science – Ecosystem Dynamics, Functioning, and Resilience -‐‑Ecosystems are dynamic in nature; their characteristics can vary over time. Disruptions to any physical or biological component of an ecosystem can lead to shifts in all its populations. (MS-‐‑LS2-‐‑4) -‐‑Biodiversity describes the variety of species found in Earth’s terrestrial and oceanic ecosystems. The completeness or integrity of an ecosystem’s biodiversity is often used as a measure of its health. (MS-‐‑LS2-‐‑5) -‐‑MS-‐‑LS4.D: Life Science – Biodiversity and Humans -‐‑Changes in biodiversity can influence humans’ resources, such as food, energy, and medicines, as well as ecosystem services that humans rely on—for example, water purification and recycling. (secondary to MS-‐‑LS2-‐‑5) -‐‑MS-‐‑ESS3.A: Earth Systems – Natural Resources -‐‑Humans depend on Earth’s land, ocean, atmosphere, and biosphere for many different resources. Minerals, fresh water, and biosphere resources are limited, and many are not renewable or replaceable over human lifetimes. These resources are distributed unevenly around the planet as a result of past geologic processes. (MS-‐‑ESS3-‐‑1) -‐‑MS-‐‑ESS3.C: Earth Systems – Human Impacts on Earth Systems -‐‑Human activities have significantly altered the biosphere, sometimes damaging or destroying natural habitats and causing the extinction of other species. But changes to Earth’s environments can have different impacts (negative and positive) for different living things. (MS-‐‑ESS3-‐‑3) -‐‑MS-‐‑ETS1.A: Engineering Design – Defining and Delimiting Engineering Problems -‐‑The more precisely a design task’s criteria and constraints can be defined, the more likely it is that the designed solution will be successful. Specification of constraints includes consideration of scientific principles and other relevant knowledge that are likely to limit possible solutions. (MS-‐‑ETS1-‐‑1) -‐‑MS-‐‑ETS1.B: Engineering Design – Developing Possible Solutions -‐‑There are systematic processes for evaluating solutions with respect to how well they meet the criteria and constraints of a problem. (secondary to MS-‐‑LS2-‐‑5) -‐‑MS-‐‑ETS1.C: Engineering Design – Optimizing the Design Solution -‐‑Although one design may not perform the best across all tests, identifying the characteristics of the design that performed the best in each test can provide useful information for the redesign process—that is, some of those characteristics may be incorporated into the new design. (MS-‐‑ETS1-‐‑3) -‐‑The iterative process of testing the most promising solutions and modifying what is proposed on the basis of the test results leads to greater refinement and ultimately to an optimal solution. (MS-‐‑ ETS1-‐‑4)
Appendix 1. Food-‐‑web diagram student worksheets. The first one allows students to identify producers, consumers, predators, and herbivores from the depicted interactions. The second allows students to imagine the various consumer interactions within this community and represent them with their own arrows, and then label them as above.
Appendix 2. Design a Better Spider Web Activity Observations – sketch a picture of your web design. Observations – sketch pictures of several of your classmates web designs.
Were any of your classmates webs similar? What features did they have in common? Hypothesis: (which one of classmates web do you think will capture the most prey) Why do you think this?
Data Collection WEB CREATOR
WEB DESIGN
# PREY CAPTURED
ME
Conclusions Which web performed the best (captured the most prey)? Were any general designs better than others? Why was this web better? Did you accept or reject your hypothesis?
