Hypermedia Applications for Distance Education and Training Manfred Thüring*, Jörg Hannemann*, Jörg Michael Haake** * empirica GmbH, Communications and Technology Research Oxford Straße 2, D–53111 Bonn 1, F.R.G. emp–d!{MANFRED, JOERG} ** Integrated Publication and Information Systems Institute (IPSI) Gesellschaft für Mathematik und Datenverarbeitung (GMD) Dolivostraße 15, D–64293 Darmstadt, F.R.G.
[email protected]
1 Introduction Almost all sectors of modern society have to cope with a rapidly growing amount of information. The knowledge required from persons living and working in such a society is continuously expanding and gets more complex everyday. Education is no longer the exclusive business of schools and universities but has also become a matter of concern for enterprises training their employees. In order to provide products and services of high quality, companies must ensure that their personnel is – and remains – highly qualified. This situation has not only caused a considerable increase of public and private investments in education within recent years (Zimmer, 1990), it has also transformed learning from a process delimited to an individual’s youth into a life-long activity that accompanies work and employment. It is this very feature of learning that serves as a catalyst increasing well known issues in education and training: ♦ The spatial distribution and time constraints of learners lead to difficulties in coordination and integration of training into everyday work. ♦ Innovation cycles of information are sometimes faster than education and training programs for conveying this information to a larger group, i.e., a course may be outdated even before each participant has accomplished it. ♦ The potentials of multimedia materials are not yet fully exploited for today’s teaching nor are they optimally integrated into facilities for education and training. ♦ Inadequate or missing tailoring of information to the background and knowledge of the individual learner reduce the efficiency of courses. In order to cope with these problems in a cost-efficient way, new forms of education and training are required which draw on the benefits of telecommunication. Such services ♦ increase flexibility with respect to the location and time of learning for groups as well as individuals, ♦ allow fast and easy update, revisions and extensions, ♦ provide access to multimedia documents and materials, ♦ improve the “individualization” of education by adapting training procedures and materials to the needs and skills of the individual student. Using the potentials of telecommunication, these requirements can be met by a value added service which enables students as well as tutors to share hypermedia applications and to communicate about them. Such a service could offer hypermedia courses for learning and teaching in a broadband network and allow its users to access these courses from different locations and at whatever time they choose. Moreover, it should provide facilities for synchronous communication (e.g., audio or audio/ video connections, telepointer, etc.) as well as for asynchronous communication (e.g., email, support for file transfer, etc.). In summary, we propose a service for distance education and training that is centred around hypermedia applications based on broadband networks and enhanced by communication facilities or even
groupware features. In the following sections, we will elaborate this proposal in more detail. We start by introducing the main characteristics, problems and user requirements associated with hypermedia applications in section 2. In the third section, we present an interface for hypermedia applications suitable for education and training. Its usage for different types of learning is described in section 4. Finally, we summarize our approach and discuss its implications for broadband services and networks in section 5.
2 Hypermedia Applications: Characteristics, Problems and Requirements A hypermedia application can be characterized as an electronic document which consists of chunks of information called “nodes”, and relations between these chunks, called “links”. Similar to the Dexter Hypertext Reference Model (Halasz & Schwartz, 1989) we distinguish between two types of nodes (Thüring, Haake & Hannemann, 1991): Atomic nodes can contain any type of information, such as text, graphics, sound, or even video. Composite nodes can represent sets of nodes as well as complex node-link-structures which may contain other composites thus constituting a hypermedia application with different structural levels. Links can either connect complete nodes or only parts of atomics nodes, such as selected graphics or pieces of text. These components can be used to create any number of document structures and thus form the basis for “individualization”, i.e., for developing training materials according to the needs and skill of particular individuals or groups. The resulting structures may considerably vary in their complexity. For example, an application which only consists of atomic nodes and links forms a flat net, while an application which contains nestings of composite nodes constitutes a layered net. The presentation of a hyperdocument is ususally accomplished by a presentation interface which enables users to navigate through the document by traversing links, opening nodes and looking at their contents. Users interacting with a hyperdocument in this way may encounter several problems. It is well known that they may suffer from a missing or insufficient understanding of the document structure (Monk, Walsh & Dix, 1988), may have difficulties comprehending the content (McNight, Dillon & Richardson, 1991, Foss, 1989) and can “get lost in space” (Conklin, 1987, p. 38). Obviously these problems are severe obstacles for a value added service which is built around hypermedia applications for distance education and training. Since its success definitely depends on the ability of the user interface to ensure efficient navigation and adequate understanding, it has to meet the following requirements: 3. It has to provide dedicated facilities for orientation, i.e., it has to: • represent the document structure, • indicate the student’s current location in the structure, • support the reconstruction of his way to this location, and • offer clear options for moving further on. 4. It has to offer convenient navigation tools which can be intuitively understood and enable students: • to move forward as well as backward, and • up as well as down in a layered information net. 5. It has to support comprehension by increasing the coherence of the presented document, i.e., it has to: • reduce the impression of fragmentarization of information that may result from splitting up the document into different nodes, and • indicate the semantic relationships between nodes. In the following section, we describe an interface for hypermedia applications which fulfills these requirements. It is part of the hypermedia authoring environment SEPIA (Streitz et al., 1993) and
is called SPI (SEPIA’s Presentation Interface, see Hannemann, Thüring & Haake, 1993). SEPIA supports the creation of hypermedia applications by providing specific net and paths editors (called “activity spaces”) and by automatically mapping the resulting rhetorical structure of an application onto a presentation interface. Furthermore, it supports updating, versioning and individualization of multimedia materials thus meeting the basic requirements listed in the introductory section.
3 A Hypermedia Interface for Distance Learning To get an impression of the basic features of SPI, imagine a hypermedia courseware about “Artificial Intelligence” (AI). This courseware could be offered by a value added service which distributes hypermedia applications for education and training in a variety of domains. One course of the AI courseware treats one of the central philosophical issues of AI, i.e.: “Can computers think in the same way as humans do?” It represents a well known debate about this question based on John Searle’s article “Minds, Brains, and Programs” (Searle, 1980). The course consists of multimedia material which could be distributed via a broadband network and be accessed by students using SPI as an interface. 3.1 The Overall Screen Layout A ’page’ of the course – as it appears in SPI – is illustrated by figure 1. Beside the application itself, the screendump shows several navigation and help facilities (i.e., the buttons ’Navigator’ and ’System-Info’ at the top, and the arrow-shaped buttons at the right bottom). Their functionality will be described in section 3.6. The application is presented in a combined style: graphical information about the document structure is shown together with the content of activated nodes. The windows are positioned according to a stable principle: the screen is divided into four distinct areas each dedicated to display a specific type of information. On the vertical dimension the screen is split into two halfs, i.e., structural information is given on the left side while content information appears on the right. On the horizontal dimension, the screen is split into a bottom area for currently activated nodes and a top area for their predecessors, i.e., for nodes previously opened by the student.
Figure 1: User-interface of SPI
With respect to increasing the coherence of a hyperdocument, the partition of the screen along the two dimensions yields three advantages. First, it establishes a close correspondence between the
structure of the document and its presentation. Second, it provides an overview of structure which is essential for comprehension and navigation. Third, it reduces the impression of fragmentation because it temporally preserves the context of the actual node by displaying the content of its predecessor in another window. Moreover, the fixed format of the interface avoids any additional overhead which would result from opening, positioning, resizing, and closing windows manually. 3.2 Displaying the Content of Nodes According to the vertical dimension, all content is displayed in the right half of the screen. Both windows can show text, graphics, pictures or audio/video sequences. They are scrollable and can therefore display texts of any length as well as graphics and pictures of any size. The window at the bottom is reserved for the presentation of the currently activated node. When a new node is opened its content replaces the content of the former activated node in this window. At the same time, the content of the former node is moved to the window above where it replaces the information of its own predecessor. Preserving the content of the predecessor of the actual node in a dedicated window efficiently supports comprehension by reducing the impression of fragmentarization. Since the student can see the content of the old node in parallel to the new information of the actual node he can quickly detect semantic relations between both sources. As a result, comprehension becomes easier and the formation of a coherent mental representation is supported. 3.3 Displaying Structural Information Figure 1 shows that the left side of the interface conveys information about the document structure. The two windows on this side provide “graphical browsers”: they display the structure in a graphical format, are equipped with a zooming functionality, and can be used for “browsing” through the application simply by clicking on nodes. In both browsers, specific icons are used to indicate different node types, e.g., folders represent composites nodes while paper sheets represent atomic nodes that contain text. As can be seen from figure 1, the upper window on the left displays the content of the composite node ’John R. Searle contra AI’ which represents the top level of the document. This composite consists of a linear sequence of four nodes. The third node in this sequence is labelled ’Replies’ and is another composite. The display of its content in the window below shows that it contains a branching path. The path starts from an atomic node which carries the same name as the composite itself (’REPLIES’) and leads to two other nodes entitled ’FIRST REPLIES’ and ’CHURCHLAND’S REPLY’. The start node of the path is the student’s actual location and its content is accordingly displayed in the right bottom window. The example demonstrates that the interface offers the opportunity of visualizing hierarchically nested structures. While the upper window displays the context of the currently activated sequencing node (’Replies’), the lower window displays the internal structure of this node. The relation between both windows is analogous to the windows showing content information: While the bottom window presents the structure in which the student is actually located, the top window presents its predecessor which belongs to a higher hierarchical level. This means, the student has reached his/her current position by opening the composite ’Replies’ in the linear sequence. As a consequence, the content of this node is displayed in the bottom window and its predecessor (’John R. Searle contra AI’) is shown in the window above. With respect to navigation and comprehension, several advantages arise from the visualization of structural information. First of all, it facilitates navigation. The student has a clear impression of his/her current location and can easily decide where to go next. Since he/she still perceives the structure that has determined his recent moves he/she can reconstruct his/her last steps thus escaping the impression of getting lost. Moreover, he/she can see which alternative steps he/she has not yet taken and may go back to a former location in order to revise a decision.
With respect to comprehension, the visual presentation of structural information increases the coherence of the document. The student directly sees the different document levels and can quickly comprehend their relations. In figure 1 for example, he/she can easily find out that there are two kinds of replies to Searle’s Thesis, i.e., ’First replies’ and ’Churchlands’ replies’. Such information should lead to a deeper understanding because it supports the development of a mental representation (van Dijk & Kintsch, 1983). 3.4 Paths and Nets Hypermedia courses created in SEPIA and displayed in SPI may be composed of many different substructures (for details see Thüring et al., 1991). Two basic kinds of structures can be distinguished: paths and nets. Paths are illustrated by the left part of figure 1. It shows that composite nodes may contain different types of paths (see Zellweger, 1989). While the upper window presents a linear path of nodes which a student must open sequentially, the lower window presents a branching path where the student is free to decide which branch to follow. Another kind of path is conditional; it is dynamic and depends on the student’s previous actions. At a specific point in the path, the student cannot reach all next nodes any more, but only a subset which is automatically computed. A hypermedia net is shown in figure 2. In contrast to paths the nodes of a net can be visited in any order. Links have no impact on navigation, but are used to indicate semantic relations by their labels. If a net does not contain any composite nodes – as in figure 2 – it is flat and the whole left half of the screen can be used for its presentation.
Figure 2: Netview of SPI
Paths and nets efficiently support the individualization of hypermedia courseware. Paths are adequate for guiding students in a predefined way through complex information spaces and will be used whenever parts of a course must be read in a specific sequence to be comprehensible. Compared to linear and branching paths, a conditional paths provides additional support for tailoring information to the specific needs and the current behavior of a student. Since it dynamically adapts to the individual navigation, it can be employed to construct more comprehensible paths which are determined by prior information. Hypermedia nets are most useful when students do not require any guidance and will find it interesting to browse freely through a space of heterogeneous information. This
might be the case when the net offers more details about a specific concept or when it presents sophisticated background information. 3.5 Color as Additional Orientation Cue While color is often used to give hypermedia applications a more lively or interesting appearance, its function in SPI is not exclusively esthetical. Instead, color is employed as an additional cue for orientation and serves as an indicator for important correspondencies between visual objects of the interface. In the graphical browsers of our example four colors are used: ♦ Red indicates the student’s actual atomic node. ♦ Pink is the color of nodes which have been visited before, but are no longer activated. ♦ Orange is used for the student’s actual composite node. ♦ White indicates all nodes which have not been opened yet. This consistent variation of colors helps students to see where they are (red or orange, resp.), where they have been (pink), and where they can go for new information (white). Moreover, the identity of nodes which are displayed in different windows is indicated by the same color (and of course by the same names). The use of identical colors for identical objects helps students to detect correspondencies at first glance and increases the coherence of a document at a perceptual or visual level. Therefore, color can be used as a valuable supplement to linguistic cues in order to point out relations which are crucial for comprehension and navigation. 3.6 Navigation Facilities The interface of our example supports several ways of moving through the document. Different facilities for navigation are provided by: ♦ the graphical browsers ♦ a button panel, and ♦ a special tool, called ’Navigator’. Navigation in a graphical browser is simply accomplished by clicking on nodes. Another kind of navigation is provided by the button panel at the right bottom of the interface (see figure 1). The panel constists of two buttons, one for backward navigation on the left and another for forward navigation on the right. Each button contains the names of nodes which can be reached from the student’s current location. The most sophisticated support for navigation and orientation is given by another tool called ’Navigator’ (see figure 3). It can be activated by clicking on its button in the top panel of the interface. The navigator provides three types of information which are very helpful for orientation and navigation: 1. It shows the history of a reading session by chronologically listing each node that has been visited during a session. 2. It shows the currently activated atomic node which is simply denoted by the last name on the list. 3. It shows the number of hierarchical levels of the document and the student’s current position with respect to that hierarchy. The navigator does not only provide valuable information, but can also be used for navigation: It allows for direct backjumps to any location visited before simply by clicking on the desired node name.
Figure 3: The Navigator
Together, the navigation facilities of the interface offer a comfortable environment for moving through hyperdocuments. Since they are coupled with graphical information about the document structure, the danger of getting lost is minimized. First experiences show that especially the navigator provides very valuable support: It not only indicates the student’s current location with respect to different levels of the document, but also tells him how many levels he has already traversed. Obviously, this information is important for recognizing the overall document structure and therefore greatly increases the comprehensibility of hyperdocuments.
4 Using Hypermedia for Education and Training Value added services which distribute hypermedia courseware using broadband networks could be extremely useful in many educational contexts and support a variety of different types of learning. In the following three sections, we will outline a number of possible features of such services by scenarios describing different learning situations and by discussing their implications for services and networks. 4.1 Hypermedia Self Studying The following scenario is based on the assumption that a value added service offers a variety of hypermedia courses to individual users. Each course consists of different lectures which can be accessed via SPI without any further facilities for communication or cooperation. Scenario: Cathy is a customer of a value added service for education and training which provides hypermedia courseware about Artificial Intelligence. Cathy takes the courses at her PC at home. One day she selects the topic “Can computers think?” from the list of courses and opens the application. The selected course is presented in SPI and starts with an overview of its major parts. Cathy follows a path which leads her through an introductory section about AI and related philosophical issues and finally takes her to the debate between Searle and his opponents. She opens a variety of nodes which contain texts of the major arguments, show pictures of various scientists and display videos about their work. Step by step she acquires all the knowlege that is necessary to understand the debate and to form an opinion of her own. When Cathy is finished with the major parts of the application she decides to take a closer look at some details. She opens a node which represents a semantic net of
important AI concepts together with a number of AI programs. She freely explores the net and tries out some of the programs. After browsing around for about an hour, she returns to the main part and finishes the course by opening the remaining nodes on the predefined path. Before she closes the application she activates the navigator and takes a look at the list of nodes she has visited. She selects those she finds particularly interesting and copies them into another application which she will keep and elaborate by adding some notes and ideas of her own. After about two hours Cathy has finished her session and logs out from the course. Implications: In such a scenario individual users must access the multimedia information contained in the hypermedia course fast enough for comfortable use. This info can either be held in a remote multimedia data store and transported on demand to the user’s workstation or it can be provided by CD–ROM which does not support easy updates. In case of a remote multimedia data store, the information can either be stored on the user’s workstation for further use (and thus requiring lots of storage capacity) or it can be handled as transient data just for display or one–time use. Thus multiple viewing requiries multiple transfers from the store but needs only smaller buffer space. Here, updates of the courseware/information can be reflected immediately on the user’s side. The remote multimedia data store can be provided by the company/organization running the value-added service. To support a broad distribution, standard hypertext and multimedia formats need to be used, that ensure possibilities for playing the courseware on multivendor platforms. To support individual note-taking and later retrieval of visited information, either copies of the referenced material or references to the external multimedia information need to be kept in separate (private) hypermedia documents. This raises the issues of copyright infringement (when has a user the right to copy or reuse material published in the course) and the royalties (e.g., if users have to pay fees on reading ceratin information). In summary, corresponding services need to be developed that allow fast access to multimedia documents, support external references (or copies), and provide means for copyright protection and/or royalty collection. 4.2 Hypermedia Coaching The second scenario assumes that SPI is enhanced by functionalities supporting communication and cooperation between two partners, in particular between a student and a tutor. These functionalities should be based on a point-to-point audio (or even audio/video) connection which provides telepointers and means for synchronizing the presentation of hypermedia applications. Currently, this functionality is already part of the SEPIA system, but not yet fully integrated into the SPI. Scenario: Steve is a member of a company which has booked courses on AI for some of its employees. One afternoon when things are not too busy, Steve opens the hypermedia courseware from the workstation in his office and starts the course entitled “Can computers think?”. He goes through the major parts of the lesson, but after a while finds out that he is not familiar with several concepts and has difficulties in understanding some of the major arguments. When he tries out one of the AI programs embedded in the hypermedia application he is unsure whether he uses it correctly and soon gets confused about its functionality. Therefore, he decides to use the hotline which is offered by the value added service. He activates an audio connection and is immediately put through to his tutor Irene who is responsible for the course. He tells her about his problems and asks for assistance. The tutor logs into the course and uses a special option of the value added service which enables her to synchronize her computer with the one used by the student. Now she sees exactly the same part of the hypermedia application as Steve and can follow all his moves through the course. Moreover, the service provides a telepointer and a facility for floor control. Irene gives floor control to Steve and asks him to go back to the parts he does not understand. Steve selects a node from the navigator, opens it and describes his problems. Irene explains the difficult part, takes over floor control and browses to another part of the course which contains more detailed background information. She
points to some interesting nodes and finally opens a video node which shows how to use the AI program that Steve has had difficulties with. Since both computers are synchronized the student’s monitor displays all of the tutor’s actions, Steve and Irene can now watch the video together and discuss what they see. When Steve feels that his problems are solved he thanks Irene for her assistance, closes the hotline and continues studying on his own. Implications: To support hypermedia coaching, student and tutor need to access the same hypermedia course. In addition, real-time audio/video communication between distributed workstations is required. Furthermore, not only accessing the same documents but also controlling the presentation of a remote peer requires floor control and synchronized remote presentations. Telepointers can then be provided if WYSIWIS (What You See Is What I See) views are guaranteed. Thus, the following services need to be offered: ♦ shared hypermedia courses accessible by the student and the tutor, ♦ fast access to shared multimedia components of the course, ♦ realizations of flexible floor control and coupling of remote presentations including telepointers, ♦ real-time audio/video communication between student and the tutor. 4.3 The Virtual Classroom The third scenario presupposes that the facilities for communication and cooperation described in section 4.2 are not restricted to two users, but are based on multipoint connections which support video conferences together with sharing of hypermedia applications. Hence, it assumes that SPI is enhanced by the same functionalities as described in the previous scenario, but adapted to the needs of multiple users. Scenario: A company has decided to train some of its employees in Artificial Intelligence. The employees are located at different company sites and join a course in the evening once a week. When Ellen logs into the course she is greeted by her tutor John and her co-students who appear in separate small video windows on her screen. John starts the course by explaining the agenda for the evening and then opens a hypermedia application entitled “Can computers think?”. Then he takes his students through the course by navigating from node to node and by explaining the contents. Together, they try out various programs, discuss their functionality and watch a video about AI research. After about half an hour John presents some tasks which can be solved by retrieving information from the hypermedia application. Now each student has to work on his/her own. Ellen leaves the conference mode of the course and browses through the information space to find the right answers to John’s questions. Whenever she finds something of interest she copies it into an application of her own. Half an hour later, Ellen switches back to the conference mode where she and the other students present and discuss their solutions with John. After about 90 minutes, the course is over and the participants log out. Implications: To support a virtual classroom, dynamic conferences (i.e., with varying numbers of participants over time) with flexible floor control (i.e., allowing independent work as well as coaching and free conferencing) and concurrent multipoint audio/video communication channels are required. To support individual work, private workspaces need to be provided in addition to the shared or public workspace of the conference. It has to be possible to move data between private and public workspaces. An individual notebook application can be regarded as an example of such a private workspace. Thus, the following services need to be offered: ♦ real-time multipoint audio/video communication between participants, ♦ dynamic coupling of distributed applications accessing the same hyperemdia course in a conference, ♦ flexible floor control within conferences, ♦ private and public workspaces and the possibility of data exchange between them.
5 Summary and Discussion In this paper we introduced some problems of distance education and training. To overcome these problems we proposed to use hypermedia courseware. In summary our message is twofold: 1. Though hypermedia is not the ultimate solution for learning and training the open philosophy of hypermedia makes it better suited than other approaches to support a broad range of learning activities. Hypermedia provides a framework within which a spectrum of methods, techniques and tools for learning can be coordinated and deployed. 2. However, all too often hypermedia systems for learning are not well adapted to the specific task at hand. We agree wityh Hammomd (1993) that getting the interface right is crucial in learning situations. SPI – a presentation interface for hypermedia documents – which we introduced in this paper is our attempt to get the interface right. It is based on a careful analysis of critical issues revealed by using hypertext systems and provide solutions for problems such as orientation and navigation as well as comprehension and coherence. In order to demonstrate the flexibility of hypertext for learning and the potential of an appropriately designed interface we described different learning situations by three scenarios. For each of these scenarios we discussed their implications on required communication services and proposed answers to problems in distant education and training: ♦ Shared hypermedia courses that are accessible via fast communication networks provide increased flexibility with respect to the location and time of learning for groups as well as individuals, ♦ The concept of logically central repositories for hypermedia courses allow fast and easy update, revisions and extensions, ♦ Broadband networks with multimedia transport services and facilities for handling external references provide access to multimedia documents and materials, ♦ Dynamic and flexible hypermedia courseware can also improve the “individualization” of education by adapting training procedures and materials to the needs and skills of the individual student.
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