An Expert System for Instructional Design

An Expert System forInstructional DesignM. David Merrill

Utah State University

iei'~~~~~~~~=_sUr; ~~~~~~~~~~~~~~~~~~~~~~~~~AIs, t

TsT

Model: Mohandas Gandhi, circa 1937.

Ssignificant progress has beenmade in developing advanced

-~ programming techniques ena-L~ bling computer-based instruc-

tional systems to demonstrate consider-able intelligence. But instructional

li models involved in this developmenthave often been based on expediencyor the project investigator's previouseducational experience, rather than oncareful analyses of learning andinstructional literature. Many systemdevelopers are now seeking informa-

L tion about instruction and learningthat can be incorporated into theseadvanced computer-based tools.

Unfortunately, much available infor-mation on learning and instruction is

Ii rather nonspecific-requiring con-siderable interpretation to translatethese general educational principles

I into the precise rules needed to imple-i ment an intelligent instructional sys-

tem. Many key investigators of intelligentinstructional systems have computerscience backgrounds, but lack exten-sive instructional design experience.While many areas exist where availableinformation is insufficient, a consider-able amount of instructional theoryand practice exists that has beendemonstrated as effective for otherdelivery systems and educational envi-ronments. This information needs to

4 be synthesized into a systematicallyorganized body of prescriptions thatcan be coded into rules appropriate for

.j various intelligent instructional systemsunder development or to be developed.

0885-9000/87/0500-0025 $01.00©1987 IEEESUMMER 1987 25

Figure 1.Components ofcomputer-basedinstruction.

Sponsored by the Army Research Institute, HumanTechnology Incorporated, and Teknowledge Incorpo-rated, we are developing an ISD (instructional systemdesign) expert system incorporating much of what isknown about instructional design. Our system proto-type will be implemented using the Teknowledge S.1expert system shell. We expect the prototype to beoperational by mid 1987. This article overviews theproposed system and discusses types of expert knowl-edge that must be represented.ISD Expert aims at instructional designers-

designers with only minimal training in instruction,learning, and related disciplines. Its purpose is toguide instructional design decisions so that resultingproducts can more adequately implement what isknown about learning and instructional design.We have limited ISD Expert to instructional design

decisions commencing after front-end task analysishas been completed, and resulting in specificationsuseful for system implementation. ISD Expert focuseson specifications for computer-based learning materials.While many principles and practices on which the sys-tem is based are equally appropriate for other deliverysystems, the specifications resulting from system inter-action focus on computer-based instruction.ISD Expert does not include many specifications

necessary for system implementation such as screendesign, answer processing, error checking, programstructure, data structures, and programming. Since itis not an authoring system, ISD Expert does notinclude screen editors, graphics editors, or other toolsfor developing computer-based learning materials. Weexpect the system to contain explanation capability sothat designer/users can query regarding the reasoningbehind given recommendations. The system's finalversion will also include cross references to instruc-tional design and learning literature.

Functional componentsof computer-based instructionOne can conceptualize computer-based instruction

in many ways. We will identify and define componentsof computer-based instruction for which ISD Expertprovides design guidance-components chosen to rep-resent various computer-based learning materials. Wechose these components to implement different learn-ing experiences including such often-identified computer-aided instruction (CAI) categories as tutorial, simula-tion, drill and practice, and games.The proposed functional components are also

appropriate for limited forms of so-called "intelligentCAI," including experiential environments and expertadvisors. However, initial system versions do not guideknowledge acquisition for designing resident specific-domain experts or for designing strong student models(strong student models are programs simulating stu-dents and what students know).

Figure identifies computer-based learning systemcomponents. The fundamental unit of the system isthe module. Three major instructional design activi-ties are involved in preparing specifications forcomputer-based instruction: The first is to identifymodules to be included. The second is to design-thatis, describe primary components for each module. Thethird is to organize-that is, arrange and sequencethese modules for presentation to students. Key termsused in describing computer-based instructional sys-tems follow.

Modules. Modules are instruction units composedof standard components. For computer-based instruc-tion, Figure indicates that modules consist of threecomponents: (1) a content representation, (2) a trans-action set enabling students to interact with the con-

IEEE EXPERT26

tent representation, and (3) a set of strategy rulesdetermining the "next" transaction.

Instructional goals. Instructional goals-that is,instructional objectives or outcomes (not illustrated inFigure 1)-are statements about what students will beable to do (their learned performance) followinginstruction. To determine the appropriate category oflearned performance, ISD Expert contains aninstructional-goal taxonomy and rules for helpinginstructional designers analyze tasks to be learned.Classifying instructional goals is an intermediate deci-sion; it facilitates content structure determination that,in turn, facilitates instructional module identificationand course organization selection and specification.

Content structure. Content structure, not illustratedin Figure 1, diagrams important content componentsand their interrelationships. ISD Expert contains acontent structure taxonomy and rules to help instruc-tional designers select, specify, and instantiate contentstructures appropriate for instructional goals. Contentstructure serves two purposes in the design effort:(1) as content to be taught, and (2) as a means fordetermining which modules to include and theirappropriate organization.

Content representation. Also called knowledge rep-resentation, content representation is the contentmaterial with which students interact. There are twomajor categories of content representation:(1) experiential representations simulating events orprocesses and enabling students to interact directlywith those simulations, and (2) structural representa-tions consisting of specific-domain segments that canbe selected and presented to students. ISD Expertincludes a content representation taxonomy and rulesnecessary to help instructional designers select andspecify appropriate content representations for givenmodules.

Transactions. Defined in Webster's as "a com-municative action or activity involving two parties ortwo things reciprocally affecting or influencing eachother," a transaction is a mutual, dynamic, real-timegive-and-take between program and student in whichthey exchange information. Many CAI programs aredescribed in terms of frames and questions, butframes and questions are too narrow and often lead tostatic presentations. A transaction is the completesequence of presentations and reactions. ISD Expertincludes a transaction taxonomy and rules necessary

to help instructional designers select and specifyappropriate transactions for given modules.

Strategy rules. Rules for selecting the next transac-tion and determining when students should shift tothe next transaction, strategy rules also indicatewhether the learner or the system should make thesedecisions. ISD Expert contains a strategy componenttaxonomy and rules necessary to help instructionaldesigners select and specify appropriate strategy com-ponents for given modules.

Course organization. Course organization representsthe module network and possible paths that studentsmay take in traversing that network. ISD Expert con-sists of a content organization taxonomy. It also con-sists of a content structure taxonomy from whichvarious content organizations can be derived. The sys-tem contains rules for selecting, specifying, andinstantiating content structures appropriate for giveninstructional goals. The system also contains rules forselecting and specifying appropriate modules and acourse organization for those modules.

Sequence rules. Rules for selecting the next moduleand determining when students should shift to thenext module, sequence rules also indicate whether thelearner or the system should make these decisions.ISD Expert contains a sequence component taxonomyand rules necessary to help instructional designersselect and specify appropriate sequence componentsfor the content structure and instructional goalinvolved.

ISD Expert requires instructional designers toengage in three distinct activities: selecting, specifying,and instantiating. Each decision category contains ataxonomy of possible values. The first part of decisionmaking is to select the appropriate category. The sys-tem helps instructional designers make appropriateselections.

Second, designers must specify parameter values,enabling the system to recommend more refined ver-sions of selected categories. The system helps instruc-tional designers verify or provide necessary parametervalues.

Finally, instructional designers must provide datanecessary to instantiate the system. ISD expert

SUMMER 1987 27

requires and guides instructional goal and contentstructure instantiation, but the system's remainingparts result only in a not-yet-instantiated specification.A later ISD Expert version will contain guidance forspecification instantiations currently beyond the scopeof the present project.

Figure 2 illustrates instructional design decisionsrequired of the system and specifications resultingfrom each decision set. Dotted boxes indicate theinput necessary for decisions. Arrow boxes indicatedecision consultations. Document boxes indicate eachdecision consultation's specification output. Fun-

Figure 2. Instructional design decisions for ISD Expert.

28 IEEE EXPERT

damental instructional design activities involved inpreparing a specification for computer-based instruc-tion require the following eight major instructionaldesign decisions:

* Identify each module to be included-(1) Select, specify, and instantiate categorizedobjectives.(2) Select, specify, and instantiate contentstructure.(3) Select and specify course modules.

* Organize, arrange, and sequence modules-(4) Select and specify course organization.(5) Select and specify sequence components.

* Design and describe each module-(6) Select and specify each module's content rep-resentation.(7) Select and specify each module's transactionset.(8) Select and specify each module's strategycomponents.

We based ISD Expert's instructional design on theGagne assumption that different instructional out-comes require different conditions for learning."2

Categorized objectives-selection, specification,and instantiation. The first instructional design deci-sion requires determining the appropriate learning-outcome category for each task or training objectivefrom the front-end analysis. In addition to trainingobjectives or tasks, this consultation with ISD Expertrequires instructional designers to clarify actions andobjects involved-thereby determining the appropriateinstructional-outcome category. This activity outputsa standardized, categorized statement of objectives-an intermediate document and not necessarily theobjectives as they will be presented to students.

This article lacks the space to illustrate a completeconsultation with an instructional designer/user foreach instructional design decision involved. Portionsof a sample dialog will follow for the next threesteps-content structure, course modules, and course

organization. We have omitted a consultation forselecting, specifying, and instantiating categorizedobjectives. That step would output the followinginformation:

Objective type: concept classificationObjective: Given new examples of < written pas-

sages containing writing errors > the student willbe able to < identify and correct each error > with< 90 percent > correct for each type of error.

Content structure-selection, specification, andinstantiation. Traditional ISD procedures have notalways included these design tasks. Most ISD modelsinclude only a single step here, based on Gagne'sprerequisite objectives hierarchies, which involvearranging objectives to show prerequisite relation-ships.2 Component display theory is based on thepremise that there are different relationships betweencontent ideas, and that selecting an appropriate con-tent structure and its instantiation provides the basisfor more appropriately selecting instructional modulesand their organization.3-7 Such activity provides a for-mal content structure diagram or description indicat-ing relationships between content elements to beincluded. This content structure guides module selec-tion and organization, but the instruction may alsoinclude the structure as content to be learned bystudents.

An example. The system knows that the mostappropriate content structure for concept classifica-tion objectives is a kinds-of taxonomy. The followingdialog guides designers in specifying and instantiatinga kinds-of taxonomy content structure. Items shown inbrackets (such as [WritingErrors]) indicate informa-tion the system gathered and displayed to students.The dialog follows a specific hypothetical consultationand does not reflect all the available alternatives.Numbers in curly brackets (such as {3.1 }) indicatevalues on various parameters that enter into laterrules. This information is not shown to users.Designer/user response is shown in italics. The dialogis hypothetical and based on preliminary system speci-fications. Since S.1 programming is underway as thisarticle is being written, actual interactions with thesystem are not yet available.

SYS2 Fill in the blank: The student will be able to identify kindsof C - [a] -

Writing-Errors

SYS3 Do you want to specify kinds of [WritingErrors]? Y/Ny

Choose one of the following alternatives:a. Kinds of [WritingJErrors] can be classed into distinct cate-

gories. {3.1 or 3.2 or 3.3}

SUMMER 1987 29

b. Kinds of [Writing-Errors] can be classed into categories butthe categories overlap. (3.41

c. Kinds of [Writing-Errors] lie on some continuum withoutdistinct categories of [WritingErrors]. (3.5]

a

Type in the major kinds of [WritingErrors]. Press Enter twiceto indicate list is complete.

F-I [a1l

Noun-ErrorsPronounErrorsRTN RTN

Choose one of the following alternatives:a. It is not likely that the student will confuse instances of

[Noun-Errors] with instances of [PronounErrors]. {3.1]b. [Noun-Errors] and [Pronoun-Errors] are coordinate con-

cepts where instances of [Noun-Errors] may be confused withinstances of [PronounErrors]. (3.2]

c. [Noun-Errors] and [Pronoun-Errors] are coordinate con-cepts where instances of [Noun-Errors] may be confused withinstances of [Pronoun-Errors] and where [NounErrors] and[Pronoun-Errors] are ordered with respect to each other. (3.3]

a

(SYS4 and SYS5 gather information relative to continuous andoverlapping categories. They are not relevant to the current case andare not included here.]

SYS6 There are distinct ways to focus a student's attention inlearning kinds of content.

Please identify the focus of the instruction.

(The first two questions would not be asked in this situation butare included to show a more complete set of questions for focus.}

)) IF 3.2 or 3.3Is the primary focus to learn to differentiate [all from [a2]? Y/N

{6.3a}

"> IF 3.4 or 3.5Is the primary focus to learn to rank instances of [Writing-Errors]

along [C]? Y/N 16.3b}") IF 3.1 OR IF N then askIs the primary focus to learn to identify instances of

[Noun-Errors]? Y/N (6.2]

N

Is the primary focus to learn to identify instances of[PronoutLErrors]? Y/N (6.2]N

)" IF N then askIs the primary focus to learn that [Noun-Errors] and

[Pronoun-Errors] are all instances of the more general concept[Writing-Errors]? Y/N (6.1}

N

" IF N then askIs the primary focus to learn that [Noun-Errors] and

[Pronoun-Errors] are all kinds of [Writing-Errors]? Y/N (6.4]

N

" IF N then askAre [NounErrors] and [PronounFrrors] primarily Place

Holders to organize the content? This means that it is unnecessaryfor the student to learn to identify instances of these concepts or to

discriminate instances of these concepts from one another. It may beunnecessary because the student has already learned [NourLErrors]and [Pronoun-Errors]. Y/N (6.5)

y

SYS7 Concepts in a kinds-of taxonomy often have prerequisiterelationships with one another. Please indicate the prerequisite rela-tionships involved by answering the following questions.

"IF below second level in taxonomy then ask (Would not beasked in this instance)Must students be able to discriminate instances of

[Writing-Errors] from instances of [2] before they can identify ordiscriminate instances of [Noun Errors] and [Pronoun-Errors]?Y/N (7.3}

)) IF N then askMust students be able to identify instances of [Writing Errors]

before they can identify or discriminate instances of [Noun-Errors]and [Pronoun-rrors]? Y/N (7.21N

{The following two questions would not be asked in this situa-tion. They are included here to show other options]."IF N and IF 6.1 then askMust students be able to discriminate instances of [NounErrors]

from [PronounFrrors] before they can identify instances of[NournErrors] and [PronounErrors] as instances of[WritingErrors]? Y/N 17.51

") IF N and IF 6.1 then askMust students be able to identify instances of [NounErrors] and

instances of [Pronoun-rrors] before they can identify instances of[NounFrrors] and [PronounErrors] as instances of[Writing-Errors]? Y/N (7.4.)

IF N then askAre we correct to conclude that there are no prerequisites to learn-

ing to identify or discriminate instances of [NounErrors] and[PronounErrors]? Y/N (7.1]y

"repeat SYS3, SYS6 and SYS7 until the entire taxonomy has beenspecified.

SYS3 Do yop want to specify kinds of [Noun-Errors]? Y/N

y

Choose one of the following alternatives:a. Kinds of [NounFrrors] can be classed into distinct categor-

ies. {3.1 or 3.2 or 3.3]b. Kinds of [Noun-Errors] can be classed into categories but

the categories overlap. (3.4]c. Kinds of [Noun-Errors] lie on some continuum without dis-

tinct categories of [Noun-Errors]. {3.5]a

Type in the major kinds of [Noun-Errors]. Press Enter twice toindicate list is complete.

E [aJ]Noun-PossessivesNounPluralsRTN RTN


[Noun-Possessives] with instances of [Noun-Plurals]. (3.1]b. [NounPossessives] and [Noun-Plurals] are coordinate con-

IEEE EXPERT30

cepts where instances of [Noun-Possessives] may be confused withinstances of [NounPlurals]. {3.2}

c. [NounmPossessives] and [Noun-Plurals] are coordinate con-cepts where instances of [NounPossessives] may be confused withinstances of [NounPlurals] and where [NounPossessives] and[Noun-Plurals] are ordered with respect to each other. {3.3}

b



))IF 3.2 or 3.3Is the primary focus to learn to differentiate [Noun-Possessives]

from [Noun-Plurals]? Y/N {6.3}

y


Must students be able to discriminate instances of [NounErrors]from instances of [Pronoun-Errors] before they can identify or dis-criminate instances of [NounAPossessives] and [Noun-Plurals]?Y/N {7.3}

N

" IF N then askMust students be able to identify instances of [Noun-JErrors]

before they can identify or discriminate instances of[Noun.Possessives] and [Noun-Plurals]? Y/N {7.2}

N

Are we correct to conclude that there are no prerequisites to learn-ing to identify or discriminate instances of [Noun-Possessives] and[NounPlurals]? This could mean that the student has alreadylearned the necessary prerequisite information. Y/N {7.1}

y

" repeat SYS3, SYS6 and SYS7 until the entire taxonomy has beenspecified.

SYS3 Do you want to specify kinds of [Noun-Possessives]? Y/N

y

Choose one of the following alternatives:a. Kinds of [NounPossessives] can be classed into distinct cat-

egories. {3.1 or 3.2 or 3.3}b. Kinds of [Noun_Possessives] can be classed into categories

but the categories overlap.{3.4}c. Kinds of [Noun-Possessives] lie on some continuum without

distinct categories of [Noun-Possessives].{3.5}

a

Type in the major kinds of [Noun-Possessives]. Press Entertwice to indicate list is complete.

C1I [a1]

-'sNoun-Possessives-s 'NounPossessivesRTNRTN


's-NounPossessives] with instances of [-s'Noun.Possessives].{3.1}

b. [2s-Noun-Possessives] and [-s'-NouncPossessives] are coor-

dinate concepts where instances of [Us-Noun-Possessives] may beconfused with instances of [-s'.Noun.Possessives]. {3.2}

c. ['s-Noun_Possessives] and [-s'Noun-Possessives] are coor-dinate concepts where instances of ['s-NounAPossessives] may beconfused with instances of [-st_Noun.Possessives] and where [-'s-Noun-Possessives] and [-s'Noun-Possessives] are ordered withrespect to each other. {3.3}

b



)) IF 3.2 or 3.3Is the primary focus to learn to differentiate [-

's_NounrPossessives] from [-s'_Noun-Possessives]? Y/N {6.3}

y


Must students be able to discriminate instances of[Noun.Possessives] from instances of [Noun-Plurals] before theycan identify or discriminate instances of [.s.Noun-Possessives] and[-si'NounPossessives]? Y/N {7.3}

y


SYS3 Do you want to specify kinds of ['s_NounPossessives]?Y/N

N

"repeat SYS3, SYS6 and SYS7 until the entire taxonomy has beenspecified.

SYS3 Do you want to specify kinds of [-s'tNouniPossessives]?Y/N

N

)> repeat SYS3, SYS6 and SYS7 until the entire taxonomy has beenspecified.

SYS3 Do you want to specify kinds of [Noun-.Plurals]? Y/N

y

Choose one of the following alternatives:a. Kinds of [NounPlurals] can be classed into distinct categor-

ies. {3.1 or 3.2 or 3.3}b. Kinds of [Noun-Plurals] can be classed into categories but

the categories overlap.{ 3.4}c. Kinds of [Noun-Plurals] lie on some continuum without dis-

tinct categories of [Noun.Plurals].{3.5}

a

Type in the major kinds of [Noun-Plurals]. Press Enter twice toindicate list is complete.

H, [a,]-s-Noun-Piurals-esNounPlurals-ies-NounJPluralsRTNRTN


SUMMER 1987 31

[-s-NounPlural] with instances of [-es.Noun-Plural] with instancesof [-ies-Noun-Plural]. {3.1}

b. [-s.Noun-Plural], [-es-Noun-Plural] and [-iesNoun-Plural]are coordinate concepts where instances of [-s-Noun-Plural], [-es_Noun-Plural] and [-ies-NouniPlural] may be confused witheach other. {3.2}

c. [-sNounPlural] [-es-Noun-Plural] and [-ies-NounPlural] are coordinate concepts where instances of 1s-Noun-Plurall, [-esNounPlural] and [-ies_NourLPlural] may beconfused with each other and where [-sNoun-Plural], [-es-Noun-Plural] and [-ies.Noun-Plural] are ordered with respect toeach other. {3.3}

b

SYS6 There are distinct ways to focus a student's attention inearning kinds of content.Please identify the focus of the instruction.

0 IF 3.2 or 3.3Is the primary focus to learn to differentiate [-s-Noun-Plurals]

from [-es-Noun-Plurals] from [-ies-Noun-Plurals]? Y/N {6.3}

y


Must students be able to discriminate instances of [Noun-Possessives] from instances of [Noun-Plurals] before they can iden-tify or discriminate instances of [-sNoun-Plurals] from [-es-Noun-Plurals] from [-ies.Noun-Plurals]? Y/N {7.3}

y


SYS3 Do you want to specify kinds of [-s-Noun-Plurals]? Y/NN

,> repeat SYS3, SYS6 and SYS7 until the entire taxonomy has beenspecified.

SYS3 Do you want to specify kinds of [-es-Noun-Plurals]? Y/NN

)) repeat SYS3, SYS6 and SYS7 until the entire taxonomy has beenspecified.

SYS3 Do you want to specify kinds of [-ies_Noun_Plurals]? Y/NN

), repeat SYS3, SYS6 and SYS7 until the entire taxonomy has beenspecified.

SYS3 Do you want to specify kinds of [Pronoun-lrrors]? Y/Ny

Choose one of the following alternatives:a. Kinds of [Pronoun-Errors] can be classed into distinct cate-

gories. {3.1 or 3.2 or 3.3}b. Kinds of [Pronoun-Errors] can be classed into categories but

the categories overlap.{3.4}c. Kinds of [Pronoun-Errors] lie on some continuum without

distinct categories of [Pronoun Errors].{3.5}a

Type in the major kinds of [Pronoun-Errors]. Press Enter twice

to indicate list is complete.[ _1 _ [a,]

PronounPossessivesPronoun-ContractionsRTNRTN


[Pronoun-Possessive] with instances of [Pronoun-Contraction].{3.1}

b. [Pronoun-Possessive] and [Pronoun-Contraction] are coor-dinate concepts where instances of [Pronoun-Possessive] may beconfused with instances of [Pronour-Contraction]. {3.2}

c. [Pronoun-Possessive] and [Pronoun-Contraction] are coor-dinate concepts where instances of [Pronoun-Possessive] may beconfused with instances of [Pronoun-Contraction] and where[Pronoun-Possessive] and [Pronoun-Contraction] are ordered withrespect to each other. {3.3}

b



)) IF 3.2 or 3.3Is the primary focus to learn to differentiate

[Pronoun-Possessive] from [Prcnoun-Contraction]? Y/N {6.3}

y


Must students be able to discriminate instances of [NounErrors]from instances of [Pronoun-Errors] before they can identify or dis-criminate instances of [Pronoun-Possessives] and[Pronoun-Contractions]? Y/N { 7.3}

N

)) IF N then askMust students be able to identify instances of [Noun-Errors]

before they can identify or discriminate instances of[Pronoun-Possessives] and [Pronoun-Contractions]? Y/N {7.2}

N

"IF N then askAre we correct to conclude that there are no prerequisites to learn-

ing to identify or discriminate instances of [Pronoun_Possessives]and [Pronoun-Contractions]? This could mean that the student hasalready learned the necessary prerequisite information. Y/N {7.1}

y)"repeat SYS3, SYS6 and SYS7 until the entire taxonomy has been

specified.

SYS3 Do you want to specify kinds of [Pronoun_Possessives]?Y/N

N

)) repeat SYS3, SYS6 and SYS7 until the entire taxonomy has beenspecified.

SYS3 Do you want to specify kinds of [Pronoun-Contractions]?Y/N

N

SYS The kinds-of-taxonomy content structure you have specified

IEEE EXPERT32

Figure 3. The kinds-oftaxonomy contentstructure forWriting-Errors.

is represented by the accompanying diagram(see Figure 3).

Course modules-selection and specification. Wecan select course modules in two ways: First, we canprovide a module for each major objective in someprerequisite hierarchy. Second, we can identify a mod-ule set that systematically elaborates the selected andinstantiated content structure. The system will guidethese procedures, and will guide instructionaldesigners as to when each procedure may be mostappropriate. Modules are selected and organized by aset of system rules-rules illustrated in the nextsection.

I. * 6 *. I

Content organization is the module network to belearned and the paths that students can take from onemodule to another. Content organization must alsocontain the control mechanisms, menus, advice, andother components necessary to organize the course.

Course organization-selection and specification.Instructional designers must select the most appropri-ate sequence options based on the students involved,the constraints of the instructional situation, and theorganization most appropriate to elaborate the con-tent structure involved. For example, having gatheredinformation about content structure, the system knows

how to analyze that content structure to recommend apreliminary module set and a course organization(that is, an instruction sequence). Using these rules,the system recommends instructional modules andinstructional objectives for each module.

Values for the category (3.0), focus (6.0), andprerequisite variables (7.0) are associated with each setof coordinate concepts. A coordinate concept set isthe next level of nodes under a single node in thekinds-of taxonomy tree structure. The nature of thekinds-of taxonomy tree structure and rules consideringvalues on these variables determine the recommendedmodules. The following rules are not as they appear inthe actual S.1 system, but are conceptual to facilitatereader understanding. These rules do not constitutethe complete set-they are merely illustrative.

The integrative module rule. Any node with two ormore levels below defines a potential integrative mod-ule (see Figure 4). All sequences include a preintegra-tive module and a postintegrative module withinstructional modules between. The transactions inintegrative modules may include overviews, sum-maries, syntheses, and pre- and posttesting.

For the writing-errors kinds-of taxonomy contentstructure, two integrative modules exist-one for writ-ing errors and one for noun errors (see Figure 5).Instructional modules are determined by consideringeach set of coordinate concepts and the parametervalues associated with that set as determined by con-sultation with designer/users.

SUMMER 1987 33

Figure 4. The integrative module.

Figure 5. Integrative modules for Writing-Errors.

Figure 6. Coordinate conceptsets for Writing-Errors.

IEEE EXPERT34

Figure 6 illustrates the kinds-of taxonomy contentstructure that resulted from the dialog to select,specify, and instantiate content structure. The num-bered dotted boxes indicate the following possible setsof coordinate concepts:

Consider coordinate concept set 1.Rule: If focus = 6.5 (Place Holder) then no mod-

ules are associated with the set. Hence no modulesare associated with set 1.

Consider coordinate set 2.Rule: If focus = 6.3 (Discrimination) and cate-

gory = 3.2 (discrete) then the coordinate set cor-responds to a module. Hence instructional module 1= Noun_Possessives versus Noun-Plurals.Objective: Students will be able to discriminate

instances of [Noun.Possessives] from instances of[Noun-Plurals].

Consider coordinate set 3.Rule: If focus = 6.3 (Discrimination) and cate-

gory = 3.2 (discrete) then the coordinate set cor-responds to a module. Hence instructional module 2= Pronoun_Possessives versusPronoun-Contractions.

Objective: Students will be able to discriminateinstances of [Pronoun_Possessives] from instancesof [Pronoun-Contractions].

Consider coordinate set 4.Module 3 = 'sNoun-Possessives vs -

s'_Noun-Possessives by same rule.

Consider coordinate set 5.Module 4 = -s_Noun_Plurals vs -

es_Noun_Plurals vs -iesNoun_Plurals by samerule.

Branching rule: If there are separate modules in eachbranch then there is a menu option for each branch.

Map rule: If there is more than one module in abranch then a map symbol is indicated on the coursesequence diagram. If there is only one module in abranch then an instructional module symbol is indi-cated on the course organization diagram.

For the writing-skills case, the first branch has morethan one module. But branch two has only one mod-ule; hence, the first level of course organizationappears in Figure 7. The boxes with curved corners areintegrative modules; the box containing the flow chartis a map indicating more detailed course organization;the box with the diamond is a menu; and the box with

Figure 7. The main course organization forWriting-Errors.

Figure 8. The second-level course organization forWriting-Errors.

the double lines on the ends is an instructional mod-ule. The integrative module, branching, and map rulesare applied to each map symbol on the first-levelcourse organization.

The prerequisite rule. If prerequisite = 7.3 (dis-crimination of superordinate) then the superordinatemodule appears before the subordinate modules.

The prerequisite option rule. Single prerequisitemodules appear with a menu option in the courseorganization.

SUMMER 1987 35

For the writing-skills case, the main course sequencemap is further analyzed by applying the above rules toyield Figure 8's second-level course organization.Many course sequences can be obtained from variousconfigurations of content structures. The system pro-vides users with an efficient way to analyze complexstructures and to obtain a recommended set of mod-ules and a recommended course organization.

Sequence components-selection and specification.Sequence components are various on-line decisionstructures controlling access to course modules. Theyinclude menus, decision rules, information to the stu-dent, and other components controlling the sequence.Instructional designers must select sequence controlcomponents to include and provide criteria needed tooperate these on-line sequence control processes. Con-tent organization decisions produce specifications forcourse organization, usually consisting of flow chartsor structure diagrams together with criteria, decisionpoints, menu items, and other components necessaryfor implementation.To implement menus and decision points in the

above content organization, for example, consultationat this point would gather more information fromdesigner/users. Our system prototype will not imple-ment this decision.

Much traditional CAI is based on the frame (dis-play) concept, in which course organization is seen asa file of screens to be presented to students. ISDExpert takes a more dynamic approach, seeing a mod-ule not as a series of screens but rather as a knowledgedatabase together with a transaction series for usingthat database. Different types of knowledge represen-tation enable different kinds of transactions. Certainrepresentation/transaction sets are appropriate fordifferent outcomes. Selecting the content representa-tion most appropriate for the objective being taughtby a module represents an important instructionaldesign decision.

For example, associated with each module in thecontent structure are various content representationsthat are then used by transactions associated with themodule. Consultation here would gather additionalinformation to provide the selection and specificationfor this content representation. Eventually, the systemwill help instantiate this content representation.

Transactions-selection and specification. Ratherthan construct screens consisting of text and ques-

tions, ISD Expert designs interactive sequences con-sisting of numerous transactions with a given contentrepresentation. Furthermore, the system assumes thatdifferent transaction sets are appropriate for differentoutcomes. The instructional design decision selectsthat set of transactions to accompany a given contentrepresentation, and selects from that set those mostappropriate to the specific module being designed.This produces a specification for each transaction.

For example, each module has associated with it atleast two transactions. Consultation would continuehere to gather additional information about which ofthe possible transactions might be appropriate toinclude for each module. Transactions are defined by aseries of attributes determining the nature of interac-tion with students. System rules constrain transactionsdepending on content organization, content structure,and certain parameters about instructional situationsand students involved.

Ultimately, this specification should include screendesign, error checking, answer processing, and otherconsiderations not part of the initial ISD Expertversion.

Strategy components-selection and specification.Just as course organization sequences exist with on-line decisions about which module is "next," moduleorganization strategies exist with on-line decisionsabout which transaction is "next." Instructionaldesigners must select those menus, decision rules,criteria, and other strategy components necessary andappropriate for a given module. Student characteris-tics and instructional situation constraints, as well asthe instructional outcome category, help determinethese decisions.

This produces a specification for each module'sorganization, usually consisting of a flow chart orstructure diagram showing the decisions, criteria,menus, and other strategy components needed toimplement the module. Additional consultation helpsdetermine the transaction sequence within each mod-ule. This decision will not be implemented in our sys-tem prototype.

S| ince we are developing the ISD Expert proto-type as this article is being written, our initialwork seeks primarily to illustrate the feasibil-ity of such an expert system and to codify

some of the knowledge involved. We plan to demon-strate our prototype in the summer of 1987. Followingdevelopment of the prototype, we will undertake amuch larger effort to more fully implement the system.U

IEEE EXPERT36

AcknowledgmentThe Army Research Institute is funding the workreported in this article. The views expressed herein arethe author's and do not necessarily reflect the views ofthe sponsoring organization.

References1. R.M. Gagne, The Conditions ofLearning, First ed., Holt, Rine-

hart, and Winston, New York, N.Y., 1965.2. R.M. Gagne, The Conditions ofLearning, Fourth ed., Holt,

Rinehart, and Winston, New York, N.Y., 1985.3. M.D. Merrill and R.D. Tennyson, Teaching Concepts: An

Instructional Design Guide, Educational Technology Publica-tions, Englewood Cliffs, N.J., 1977.

4. C.M. Reigeluth, M.D. Merrill, and C.V. Bunderson, "The Struc-ture of Subject Matter Content and its Instructional DesignImplications," Instructional Science, Vol. 7, 1978, pp. 107-126.

5. M.D. Merrill, "Component Display Theory," in InstructionalDesign Theories and Models, C.M. Reigeluth, ed., LawrenceEarlbaum Associates, Hillsdale, N.J., 1983.

6. M.D. Merrill, "An Illustration of Component Display Theory,"to appear in Instructional Design Theories in Action: LessonsIllustrating Selected Theories, C.M. Reigeluth, ed., LawrenceEarlbaum Associates, Hillsdale, N.J., 1987.

7. M.D. Merrill, "Applying Component Display Theory to theDesign of Courseware," to appear in Instructional DesignsforMicrocomputer Courseware, D.H. Jonassen, ed., Lawrence Earl-baum Associates, Hillsdale, N.J., 1987.

M. David Merrill is an instructional design theorist, and has pub-lished widely in the field of instructional design. He led the teamthat developed the authoring system on TICCIT, an early CAI sys-tem. His Component Display Theory and Elaboration Theory(developed with Charles M. Reigeluth) are instructional design the-ories that were cited in the Annual Review ofPsychology as majorcontributions to instructional psychology. His current interestsinclude the application of Al to computer-aided instructionaldesign.

The author can be reached at Utah State University, Department ofInstructional Design, L-122, Logan, UT 84322-3025.

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An Expert System for Instructional Design