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PII: S0747-5632(98)00002-8 Intelligent Tutoring Systems as Design Albert K. W. Wu M. C. Lee Department of Computing, Hong Kong Polytechnic University Department of Computer Science and Engineering, Chinese University of Hong Kong Abstract — To build intelligent tutoring systems (ITSs) is not easy. Over the years, various attempts had been made with many problems uncovered. This paper presents the situation and proposes the notion of ITS as design to engage ITS development with more rigor. With the various related issues, principles and characteristics of design described, the ITS design problem space is elaborated. Implications from adopting such a perspective, including (a) a systems approach to ITS, (b) a paradigm hierarchy, (c) the emergence of an agent model, and (d) the need for a description language, are highlighted. We further argue that by such a rendering, more systematic collection of efforts on ITS can be achieved. It is envisaged that the discussions would help set the research of ITS in context and provide further intuition towards ITS development. # 1998 Elsevier Science Ltd. All rights reserved Keywords — intelligent tutoring systems, ITS, design, ITS as design, paradigm hierarchy 209 Requests for reprints should be addressed to Dr A. K. W. Wu, Department of Computing, Hong Kong Polytechnic University, Kowloon, Hong Kong. E-mail: [email protected] Computers in Human Behavior, Vol. 14, No. 2, pp. 209 – 220, 1998 # 1998 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0747-5632/98 $19.00 + 0.00 Pergamon

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PII: S0747-5632(98)00002-8

Intelligent Tutoring Systems as Design

Albert K. W. Wu

M. C. Lee

Department of Computing,Hong Kong Polytechnic University

Department of Computer Science and Engineering,Chinese University of Hong Kong

Abstract Ð To build intelligent tutoring systems (ITSs) is not easy. Over theyears, various attempts had been made with many problems uncovered. This paperpresents the situation and proposes the notion of ITS as design to engage ITSdevelopment with more rigor. With the various related issues, principles andcharacteristics of design described, the ITS design problem space is elaborated.Implications from adopting such a perspective, including (a) a systems approachto ITS, (b) a paradigm hierarchy, (c) the emergence of an agent model, and (d)the need for a description language, are highlighted. We further argue that by sucha rendering, more systematic collection of efforts on ITS can be achieved. It isenvisaged that the discussions would help set the research of ITS in context andprovide further intuition towards ITS development. # 1998 Elsevier Science Ltd.All rights reserved

Keywords Ð intelligent tutoring systems, ITS, design, ITS as design, paradigmhierarchy

209

Requests for reprints should be addressed to Dr A. K. W. Wu, Department of Computing,Hong Kong Polytechnic University, Kowloon, Hong Kong. E-mail: [email protected]

Computers in Human Behavior, Vol. 14, No. 2, pp. 209 ± 220, 1998# 1998 Elsevier Science Ltd. All rights reserved

Printed in Great Britain0747-5632/98 $19.00 + 0.00

Pergamon

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Current State of Affairs

We are currently in a conflicting state of affairs in the arena of learning systemin general and in intelligent tutoring system (ITS) in particular. On the onehand, we have many new systems coming one after the other under the drivederived from the rapid advent of computer technologies such as multimediasystems, workgroup computing, and so on. On the other hand, theadvancement of research in the field is modest (Clancey, 1987, 1992; Frasson,Gauthier, & Lesgold, 1996; Sokolnicki, 1991; Wenger, 1987). Although oftenwe have researchers attacking different aspects of the problem withmanifestos drafted, the field of research only appears superficially flourishing.As pointed out by Self (1990a), beneath the surface many of the results are indisarray. Little congenial aggregation and build up of wisdom has beenattained so far. This is also noticed by Collins (1992):

We have had many technologies introduced in classrooms all over the world, but theseinnovations have provided remarkably little systematic knowledge or accumulatedwisdom to guide the development of future innovations. (p. 15)

On Developing Intelligent Tutoring Systems

Developing ITS is an enterprise in view of the disciplines and complexityinvolved; and to claim for success and contributing to advance is not easy.None the less, such development works are basically design acts for producingan artifact ± a system for learning. They are also the defining characteristicsof the so-called artificial sciences that distinguish artificial from natural(Simon, 1981). (It is not our intent to delve into the philosophical discussion ofwhether ITS is art or science or engineering. Otherwise, we would get back tothe years' long discussion of whether software is art or science or engineering.)With ITS belonging to the category of artificial science, it also means design

is at its core. Unless we understand the process of design, we can hardly claimto understand the product (in this case ITS) of that design process. It is asessential to know what to make as how to make it.Therefore, it is appropriate if ITS can be viewed with a more disciplined

``design'' perspective. This seems reasonable from both pragmatic andtheoretical viewpoints. As such, this would mean subjecting ITS to morerigorous and disciplined treatment as taken in other engineering practices forproduction, assessment, and maintenance.

TOWARDS INTELLIGENT TUTORING SYSTEMS AS DESIGN

Engineering Design Versus Intelligent Tutoring Systems Design

In the last half century we witnessed a steady growth in the development ofengineering design. In civil and structural engineering, some comprehensive

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approaches or design methodologies together with design notations have beendeveloped. In other areas of engineering, such as electrical and electronicengineering, we can also find some developed design approaches coupled withtheir notations (e.g., component symbols and/or logic symbols). The advent inengineering design has also ushered the notion of artifact ± product as acomprehensive whole whereby a systems view is presumed; and the emergenceof design as a discipline embodying its school of principles and techniques.This, however, contrasts markedly with the design of ITS where we have notyet reached such a mature stage.Conventionally, the design of ITS has been ad hoc and is usually conducted

in a piecemeal fashion with some parts of ITS emphasized and othersneglected (Lippert, 1989; Self, 1990b; Wenger, 1987). This has led to not onlyincomplete products but also outcomes failing to live up to expectation. Manycurrently claimed ITS design approaches thus fall short of the more rigorousmeaning of design from an engineering viewpoint.

On ``Design''

Owing to the much progress in the past quarter century on the topic, design ±or the study of design methods in general ± has now emerged as a discipline inits own right hallmarked by a number of texts such as Alexander (1964),Dasgupta (1989), and Simon (1981). Based on a slightly modified versionfrom Kalay (1987), design can be defined as:

an ill-understood process that relies on creativity and intuition as well as judiciousapplication of scientific principles, technical information, and experience, for thepurpose of developing an artifact, real or abstract; or an environment that will behave ina prescribed manner. (preface)

In other words, the concept of design entails the following:

1. A systems view to artifacts. That is, an artifact is treated as acomprehensive whole. Thus, the kind of ``design'' that only handles apart of the problem with its relation with others ignored deviates fromsuch a systems perspective.

2. Design is a process. That is, a continuous undertaking that is bothiterative and evolutionary (Popper, 1972, p. 145).

3. Design demands heuristics. Since design is an ill-structured process, thereis always a ``bounded rationality'' of design bearing some ``satisficing''nature (Simon, 1982).

4. Design involves both prescription and description. For design involvesboth the prescribing of steps, a kind of applying principles to synthesizeacts, and the describing of the process, a kind of illustrating andexplaining the actions.

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In addition, in order to effect, design also embodies with it the followingmajor principles and techniques:

1. Abstraction. The approach whereby a complex artifact is comprehendedby singling out its abstracted essence with details suppressed (Shaw, 1984,p. 158).

2. Modularity. The approach whereby a complex artifact is divided intomodules or components in order to gain intellectual control of thedevelopment (Gannon, Hamlet, & Mills, 1987; Parnas, Clements, &Weiss, 1985).

3. Encapsulation. With encapsulation, the internal details of a moduleimplementation are hidden such that a user of the module will not beaware of the module internals, except the visible module interfaces.

4. Hierarchy. This principle implies the segmenting of an artifact into somerelated layers or levels of abstraction with each layer capturing the totalartifact essence in some way. As such, this would enable both intra- andinter-level connections of different system modules at different abstrac-tion levels (Mills, 1986; Simon, 1981).

Further, design also brings in the notion of design as problem solving(Newell & Simon, 1972). Here, design is viewed as dealing with a problemconsisting of its problem space; with the solution being some state(s) in thespace. The process of design is then the traversing of problem states byapplying operators transforming from one state to another until the goal stateis reached.Therefore, with the aforementioned as the basis, when we are working

towards ITS as design, we are assuming a rigorous sense bearing theseconcepts and principles.

IMPLICATIONS

Working towards ITS as design brings forth the following implications.

A Systems Approach to Intelligent Tutoring Systems

When we think of ITS, our conventional picture is one of a computer-basedsystem with design following some set of designated guidelines and rules.However, this is far from ideal. Seldom do we have an ITS constructed from atotal systems perspective using some ground rules. This can be exemplified bythe many works reported that most ITS tend to focus on certain narrowaspects of the problem in a piecemeal fashion.

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However, in engineering and urban planning a series of abstraction

techniques emphasizing engineering concerns, including careful delineation of

problem/task levels and related methods and principles so as to facilitate

design, specification, checking, and verification, has been in place. None the

less, we are yet to have such treatment of ITS as total systems. It also seems

that such a direction for ITS is less motivated than in other areas. Perhaps, the

current state of ITS does not yet face the kind of crises encountered in these

areas. Thus, the attempt to develop a body of knowledge or ``discipline''

parallel to them is less motivated by any perceived crisis in this field than by a

deep sense of dissatisfaction with the current state that is riddled with

unsystematic results.

By adopting a design perspective with ITS viewed as an artifact ± a

comprehensive whole ± a systems approach is implied. That is, the problem of

developing ITS is addressed holistically. Rather than dealing with each ITS

part separately in a piecemeal manner, a total systems picture is taken for the

problem. In addition to the final product, the notion of design also denotes the

art, craft, and science towards making the product. In other words, it lends the

artifact, in this case ITS, to general features of systems and design principles.

Problem Space of Intelligent Tutoring Systems

Design as problem solving prompts us to probe for the problem space of ITS

which is related to the concerns of how ITS is viewed at different levels of

abstraction. Abstraction is a very effective means for one to obtain a

comprehensive picture on complex artifacts such as ITS. In order to provide

proper linkage between abstractions, the hierarchy principle is needed (Athey,

1982; Simon, 1982; Weinberg, 1975).

We can group our major concerns of ITS into a problem space of three

major abstraction layers with the instruction ± interaction (or instruction)

layer at the top, the processing layer at the bottom, and the architecture layer

in between.

1. Instruction ± interaction. This is the topmost layer where the (intelligent)

tutoring problem is treated in an abstract or logical manner. Here, the

external or outer behavior of ITS is the major concern. The instruction

level view of ITS also defines the interaction between the machine tutor

and any instructional tasks for effecting instruction; with the machine

and the learner viewed as the teaching and learning agents, respectively.

Objects of interests manipulated at this level include strategies,

approaches, communication and coordination of high level resources,

etc. (More elaboration on these will follow.)

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2. Architecture. This is the middle layer in the hierarchy between theinstruction ± interaction and the lower level processing layers. In a way, itis the interface between the instruction ± interaction and processinglayers, although in principle we can describe all the high-level (i.e.,instruction level) behaviors by the processing layer entities andmechanisms without the need of any intermediate layer. However, formany purposes such descriptions are too detailed and contain too muchinformation for comprehension. To better understand how the instruc-tion ± interaction behavior at the high level is realized, we need to abstractfrom the details of the processing level to a higher level of description ±thus, the architecture layer. Whilst on one hand it is an abstraction of thelower processing level, it is also a (virtual) implementation of the upperlevel solution on the other. Basically, the objects of interest in this layerare (a) the capabilities and performance characteristics of the aggregatedfunctional components abstracted of entities in the lower processing leveland (b) the organization and ways in which these functional componentsare interconnected.It should be noted that the detailed inner working ofindividual components will not be taken at this level. However, the waythese components are combined to effect solution is the concern here.Thus, it is called the ``architecture'' level.

3. Processing. This is the lowest level where the detailed processing andinteroperations of processing components are performed in realizing theITS behavior. For example, the processing of data and controlinformation between and within components are the matters of interestat this level. Thus, at this level, the main issues are the design of theindividual processing components and the design of data for interopera-tions and communications. In other words, the internals of individualcomponents are to be decided and appropriate low-level interconnectionsare also chosen at this level. How knowledge is represented andmanipulated with what scheme is also determined here.

The relationship between the three layers of instruction ± interaction,architecture, and processing is depicted in Figure 1. In Figure 1, the topmostinstruction ± interaction layer is responsible for more ``visible'', ``external''behavior dealing with the learner, while layers further down the hierarchy dealmore with the ``nature'' or ``internals'' of the ITS. Depending on what levelsare considered appropriate to them, two different ITS workers may choosedifferent levels to work on with two very distinct sets of functional concernsdefined. This also accounts for the many seemingly disparate research resultsreported in the literature.It is important to realize that the purpose of devising a hierarchy is to aid in

design, analysis, and tackling of problems. The designation of three major

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layers for ITS is not meant to be fixed and final. For different design needs we

may need to further introduce levels or sublevels between these ``major''

layers. It is also not surprising if there are some minor overlaps between two

adjacent layers although their individual purposes are clear. This is the same

as for many other areas such as communications where having a 100% clean-

cut delineation of the different layers is not possible (Tanenbaum, 1989).

The Problem Recast

Approaching ITS as design with its layers of problem spaces also effects a new

look. As such, the whole problem of achieving machine-based tutoring is

recast as dealing with the layered sets of problem (sub)spaces. Approaching

ITS also becomes the exercise of working with these layers of problems in

turn. In the sense of problem solving as search, states in the ITS design space

can thus be interpreted as some (partial) models of ITS with its related

conditions, methods, and desired/expected outcomes ± a certain (partially)

developed view of ITS ± in its operating layer. Each of the layers also has its

particular concerns calling for its own related set of principles, methods, and

disciplines. For example, the concerns in the instruction ± interaction layer

may call for the disciplines of sociology and anthropology for (coordination)

methods.

Table 1 gives a brief summary of the concerns in these layers in the ITS

context. The examples in the table are for illustrative purpose only and they

are not meant to be exhaustive.

Figure 1. Relations of solutions between different layers of an ITS space.

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Under such a recast, one can readily observe that the many approachescurrently taken for ITS are mainly in the architecture and processing layers.As different approaches may suit for different layers, many current problemsof ITS are perhaps due to misplacing or misuse of the approaches. Indeed, inhandling a problem it should be made clear at which level (i.e., the context) itis situated; otherwise, it would not be dealt with duly.

Hierarchy of Paradigms for Intelligent Tutoring Systems

It is obvious that, given the different emphases at different abstraction levels,no single paradigm or approach can provide a satisfactory picture for all theITS layers. However, such a situation is alleviated by adopting a systems viewwith layers (Newell & Simon, 1972). Corresponding to the layers, a parallelledhierarchy of paradigms could be adopted with ``agents'' at the top (Figure 2).Individual paradigms are not dealt with in detail here as discussion of themcan be found elsewhere (Wu, 1993, 1996).As shown in Figure 2, the agents paradigm can be further refined and

``aggregated'' with lower-layer paradigms for modeling an ITS. The higher aparadigm is located, the more it is concerned with high-level entities andcommunication protocols for ``external'' behavior. On the other hand, thelower-layer paradigms are more concerned with ``internal'' behavior andimplementation. Such an arrangement also helps integrate different para-digms in a more coherent fashion. For example, in Figure 2, the agents canaggregate and couple with communication (Wenger, 1987), which furthercouples with other paradigms in accomplishing intelligent tutoring. Note thatthe principle depicted in Figure 1 always applies here: solution at an upperlevel (paradigm) should be translated as constraints imposed on the layerimmediately below. As such, it also avoids the majority of the problems of ITSbased on a single paradigm by properly diverting them to the right contexts(levels). For example, by first adopting an agent paradigm in recognition ofmultiple experts with overlapping knowledges, previously inhibited overlap of

Table 1. Layers and Their Concerns

Layers Concerns Example of concerns

Instruction ± interaction ``External'' solution structures andprocedures

What instructional strategies andinteractions are to be performed forinstruction?

Architecture ``Functioning'' and ``structuring'' ofcomponents towards achievingsolutions

How are the different knowledge-bases to be organized to support aparticular kind of teaching strategy?

Processing Components' ``internals'' How is knowledge structured toachieve dynamic retrieval of subjectcontent?

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knowledges based on the knowledge approach is no longer taken as

inconsistent but accepted and treated as natural. From then down the

hierarchy, if it is implemented via the knowledge approach, the whole agents'

view (with ITS knowledge distribution strategy amongst agents) is then

translated as impositions on the lower-level multiple knowledge-bases and

demands for their containing of common knowledge. Overlapping of

functions among the internal agents is also permitted. Of course, this renders

into a control problem at the lower levels. Additional domain specialist agents

operating on different knowledge representations with different viewpoints

may also be added to the scene to cater for the situation.

The Emergence of an Agent-Theoretic Approach

In previous sections, we have assumed a general meaning of agent ± some

entity capable of initiating action. While agent is a very natural and direct way

to mimic human, the concept however needs to be developed more rigorously

for better dealing with the problem. By taking an agent-theoretic approach

with agent being viewed as some semi- or fully automatic entity capable of

initiating actions (Seel, 1989), a more prescriptive paradigm for ITS at an

upper level of abstraction is envisaged. This view is also advanced by the

recent growing importance of distributed artificial intelligence theories. In

addition, it would alleviate the problems related to the traditional

``cooperative experts'' paradigm that has long been attacked due to its

unclear specification; see Self (1990b) and Winkels and Breuker (1990), for

example. As this work is not about agents, readers may refer to Jennings and

Wooldridge (1996), Kearsley (1993), and Wu and Lee (1995) for more on the

topic.

Figure 2. Hierarchy of paradigms: an example.

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The Need for an Intelligent Tutoring System Design Notation

As highlighted in the previous section, the design process contains mixedactivities of description and prescription. No matter its description orprescription, some kind of notation or language is required. With ITS asdesign, it implies in addition to design principles the designation of someproper set of design notation. The conventional use of natural languagesubjected to various interpretations would not be adequate. Even if there isthe assistance of diagrams, the outcome may still be unsatisfactory in terms ofclarity and preciseness. Design tools for conventional software systems basedon an input ± process ± output paradigm cannot alleviate the situation either,as they do not suit the interactivity, knowledge-orientation, and adaptabilityrequirements of ITS. Given the many levels of problem (sub)spaces, thisdemand for a design notation could not be emphasized enough. Indeed, withmore than three decades, the instructional system movement still lacks acomprehensive notational system for description and comparison purposesand for promoting new design.As an essential requirement for disciplined design is the availability of some

design notation (cf. electronic engineering design with its symbol sets fordifferent levels of abstraction), we anticipate the same should be developed forITS.

CONCLUDING REMARKS

The development of ITS has long suffered from its diversity and complexity.Often research efforts are scattered and dispersed with problems and debatesdiversified. The call for a unifying perspective to aid in cohering current worksof cognitive and instructional sciences and knowledge-based systems isimminent.With ITS as design, a new and more comprehensive treatment of ITS can be

taken. While the use of design concepts such as abstraction and hierarchy isnot new in many instructional and discourse planning systems, the currentdiscussion, however, provides a more encompassing view of ITS. Otherwise,results could not be organized in a more cohesive manner.Indeed, viewing ITS from a wider systems perspective calling for a

progressive hierarchy of paradigms is both innovative and rewarding. For onething, it enables us to envisage a better structuring of the problem. Besides,many of the previous theoretical problems associated with intelligent tutoringmight also be handled in their right contexts. Whilst implementing ITS isnever easy, the current treatment has none the less set a new perspectivetowards the problem. For further advancement in the direction, a languagefor design is needed. Currently, our efforts towards ITS as design concentrates

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on the devising of a principled methodology with a multilevel design languagefor ITS (Wu, 1996, 1997). More experimental work remains to be done. Nonethe less, the notion proposed here could form the basis, suggest possibilities,and facilitate clearer technical and theoretical discussions for the developmentof the field.Perhaps, shall we start building a theory for ITS based on this first

principle, ITS as design, now?

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