Stephen Lower Simon Fraser University Burnaby. B.C. V5A 1S6
George Gerhold Western Washington University Bellingham. 98225
Stanley G. Smith ~niverktyof llhnois Urbana 61801 K. Jeffrev Johnson University of Pinsburgh Pittsburgh, Pennsylvania 15260
I
Computer-Assisted Instruction in Chemistry
and John W. Moore Eastern Michigan University Ypsilanti 48197
The ability o f a computer to engage a student in a dialog.. ..can be used in a variety of ways to improve the quality o f instruction..
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Computer-assisted instruction (CAI) refers t o those applications of computers in instruction where a student engages in a dialog with a computer program to achieve a well-defined and measurable understanding or skill. A computer system t h a t can accommodate a laree " number of such interactive prugrams, all of which are readily accessible tostudents who umish 11, use them. cnn support a significant part of the insrructional load in a gi\.en course or curriculum. This arricle attempts to summarize the current status of CAI in chemistry instruction. T h e authors have a total of fnur decades of exprrience with diverse CAI systems in different environments. and we hope that the opiniuns and h c t s collerted here will he of value t o potential users of CAI. ~
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Uses of CAI Theability ofa wmputer t ~ e n g n ~ e a s t u d eina n t dialog (see Fie. 1 ) about some specific topic, docalculntions rapidly, plot graphs and draw molecular structures, and simulate real-life situations can be used in a variety of ways t o improve t h e quality of instruction and to extend the traditional educational objectives of courses. CAI can profoundly alter t h e manner in which a course is presented if sufficient high quality CAI material is available and an instructor is willing t o adjust the roles of lectures and other class activities to accommodate it. Some of the principal ways in which CAI has been incorporated successfully into chemistry courses are listed below.
Figure 1. A student in dialog with the Piato computer-based teaching system at the University of Illinois.
Pre-lob CAI simulates a laboratory exercise in advance. Students are reouired to assemble aooaratus. take readines. and eamvute and .. mttrprrt reiultr i w f t re doing tile qame thmg in the lalm~tr,ry.'l'hi* ensures that each xtudent i r adrqunrrly prrpnrnl 10 lrcncfit from rhr laboratory session. Past-lab CAI allows s student to enter eltperimental results into the computer for verification of the reasonableness of the data, gives assistance with treatment of the data, checks on correctness of calculations. and discusses the meanine of the results. These functions can hr rnpdly nnrl armratel! pcrfmned hy thr wmputar in most Problem-tutorial CAI provides interactive help on assigned cnsrr, nlinwmy the instructor rune t u disruis speriiic, iwJi\~idu31 homework problems. Built-in drill and remedial review ensure that problems with students. students achieve understanding of the reasoning leading to a probLab-eztension CAI simulates experiments that students already lem's solution, as well as obtaining the correct answer. have performed in the laboratory. Students can obtain an intuitive Objeetiue-directed tutorial and drill complements,supplements, feeling for the properties of materials or the effects of changing exor reolaces lecture and textbookstudv on asoecifictooic. A student perimentalconditions, even though an experiment may be too times r l r m a ienrning objective or a ~oncrptthar hnc been identitied n* copsuming or require too much equipment to be repeated. (Some nn important part of I I I rouwr,nnd ~ a CAI program ruulm nnd r l u i n r ~ experiments in kinetics and eounter-current extraction fall in this the htudmt un the zubjerr Appropr~nwdrdl, review, nnd rrmdintlm class.) are included. Lob-rub.4ilurr CAI h a been used simulate experiments thnr Quiz- or test-mode CAI programs can generate tests either by cannot br run in the lhbwutury h e c ~ ~ ~ ~ t l w y a r e t ~ n , d itM~llikan ffir~~it random selection from a pool of related questions or using questionoil drop) or because the necessary equipment is not available (nmr, generating programs, presenting each student with a quiz that is mass spectrometry). unique but equivalent in difficulty to quizzes presented to other students. Such tests mav be used as oradice for in-class exams or thev Strategies In CAI mny wrve a< wrrkly quirws 'l'hry oitrr the advanrages of unit'cmm General strategies adopted in CAI may be classified a s mnrrnt and quality in mt~ltiple-sectiun rmrsrs, insrnntnnm~~ grndmg drill-and-practice, tutorial, simulation, and gaming. Most and iredhsck t ~ students, r and n~~to~~~aricmtryofsn~rrsinan~~n-l~ne programs include several strategies in various proportions, hut gradebook. for simplicity each application t h a t we describe in t h e following paragraphs emphasizes only one. Author to whom corresoondenee should he addressed. ~
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Volume 56, Number 4. April 1979 1 219
CAI can profoundly alter the manner in which a course is presented. .
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A veN elementarv examnle of drill-and-oractice is an introductory exercise For teaching the names and symbols of the elements. The program selects the symbol of an element a t random from a list. If the student enters the correct name that element is removed from the list and another is selected. Elements that are not correctly named remain in the list so that eventuallv the student is recvcled through - the items requiring the most practice. A more complex problem to which a drill-and-practice strategy can he applied is the determination of oxidation numbers. The material can he structured so that monatomic ions and hinarv comoounds are nresented first. The student's mastery of simple examples canbe checked by keeping track of the fraction of incorrect answers. This provides a basis for the program to decide when to introduce harder problems. Eventuallv the student reaches ions containing-hvdroeen . - and oxygen and, in turn, noninteger oxidation numbers. Such a program makes use of the computer's ability to branch upon satisfaction of a preset condition. The program might also contain diagnostic routines to detect common errors, such as ignoring thenet charge of an ion, and might choose examples that check whether the error is repeated. Even these simple examples represent a major advance over what would be possible without CAI. Ordinary classroom drill is time-consuming, boring for the teacher and many students, and not readily individualized to meet student needs regarding amount of practice or distribution over levels of complexity. Moreover, ordinary drill is often left undone. With an appropriate CAI program, length and sequencing of drills can be adjusted to each student's needs and performance, exercises are readily available (often a t times when teachers are not), and an element of fun can often be introduced by making a game of the drill. Also, some students who are embarrassed to show their "ignorance" to a teacher or tutor are willing to do so to a computer. Tutorial CAI presents information or expository material in small segments. The student's active participation is required by including many opportunities for student responses. Based on these responses the program decides how rapidly material should he nresented and/or how much should he covered. For exampie, beginning organic chemistry students can develop the basic ideas of the common nomenclature system by evteniion of their knowledge of the names of simple salts. The tutorial interaction outlined below starts by asking for the name of NaC1, then adds the name of a new group, CH3, and asks the student to develop the names of CHaCI, CH3CH2C1,CH30H, etc. ~
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COMPUTER The names of many compounds are simply derived from the groups or atoms which must be assembled to form the molecule. For example: What is the name of NaCI? STUDENT sodium chloride COMPUTER The CHs group is called methyl. What is the name of CHaCl? STUDENT methyl chloride COMPUTER What is the name of CH3CH2CI? STUDENT ethyl chloride COMPUTER When an OH group is attached the compound is an alcohol. What is the name of CH30H? 220 / Journal of Chemical Education
STUDENT methyl alcohol In this type of dialog i t is essential that help be available should the student not he ahle todevise the expected response. Also, alternative right answers such as chloromethane should be recognized with appropriate comments. Common errors such as writing methylchloride can receive specific comment Simulation is often used in CAI programs to generate data which would take too long. be too dangerous, or cost too much to obtain in the laboratory. ~ x ~ o s u r esuch t o data augments students' experience of the ways that various quantities or substances interact in complex systems. The student can alter each parameter and observe the result, just as in a real experiment. Simulation is especially effective when combined with graphics and embedded in tutorial dialog that checks whether the student understands the objective of the simulation and can interpret the results correctly. For example, one simulation desiened to . orenare . students for their first encounter with a single-pan analytical balance displays a line drawing of the balance, showing all controls. The student can manipulate each control by touching the display panel, adding or removing weights, releasing the pan, and so on. Mistaken readings and misuse of the balance are corrected without wear and tear on the instrument before the student enters the laboratory. Many programs can be made more interesting by introducing gaming features. When some kind of score is kept or competition with others or oneself is introduced, student motivation soars. In one oreanic chemistrv course manv students have received cmsiderahle enjoyment from a program that allows them to compete against another student a t a different terminal. One student ihooses a compound that the other must try td synthesize, and the computer serves as an impartial judge of the efficacy of the proposed reactionsequence. If the second player's synthesis is not correct, the first student must then attempt it. The player who makes the compound first wins.
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Implementation of CAI Strategies Space is not available for a detailed description of how the strategies just described might be implemented on a given CAI system for a specific instructional task. The flow chart in Figure 2, however, indicates in general how a single numerical nrohlem mieht be nresented to a student. The algorithm outlined in &urP 2 is by no means the only effectivr cine, and the discussion that follows is necessarilv owrsimplificd and ~restricted to a particular type of question. Our intention is to eive a brief. incomnlete indication of some of the nroerammine problems that m i s t be faced in order to make a &nput& interact effectively with a student. Developing a single concept will usually require a series of questions, perhaps similar to this example or perhaps of other types. Writing a complete lesson obviously involves a significant quantity of programming. In this example the computer begins by generating a problem, perhaps by inserting randomly selected numbers or words into blanks in a skeleton text. After the problem is printed the student is required to respond, and the computer accents and analvzes the student's resnonse. I n the case of numeric results the program might compare the response to a ranee of accentable values. such as a deviation of i1% from the correct answer. I n the case of alphabetic responses it is very convenient to he able to ignore common misspellings of words and to be ahle to pickdesired keywords out of sentences. For example, the program ought to recognize that the re-
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sponses "add strong base," "treat with caustic," "add alkali," or "throw in alkalai" are essentially the same, just as a human instructor would. The program ought not to confuse these statements with a response such as "add acid until alkali is neutralized," even though the latter contains the keywords "add" and "alkali." Based on its analysis of the student response the computer carries out some appropriate action, as indicated in Figure 2. A very important feature of any CAI program is the anticipated incorrect answer. The experienced teacher can predict a numher of errors that students mav make. and the comvuter should recognize these errors, print a n app;opriate comment, and nermit the student to trv . aaain. - In most cases there will he several anticipated incorrect answers, each with a unique comment. It is quite easy to program a computer to force the student to solve problems in a particular way; it is considerably more difficult to have the computer build on the correct portions of the student's solution by recognizing and correcting common errors. The procedure in Figure 2 imposes a particular way of working a problem on a student only if the student's response is "help" or contains unanticipated errors. Several other typical features of CAI programs are illustrated in Figure 2. The student can initiate a hranch to the next question by responding "skip," or obtain a more detailed tutorial using "help." A counter, N, keeps track of how many
1
Generate question, problem, tutorial material, graphics. andlor simulation using stored data and randomly selected
I
\
Read and interpret student response.
0
0 Print reinrorcing mes-
question
sage and go to next ques-
tion or repeat this rrame.
appropriate (anticipated) I Unrecognized
Type t h e nane of the element as i t
is placed in this P E R I O D I C T A B L E What is the name of
Mg
d B
c
N
O
FNe
22 Names t o go For assistance w i t h a name prerr HELP. TOq u i t press B A C K . Figure 3. CAI presentation of drill on naming elements.
times the student has attempted to answer the question. After the third try a detailed answer is given, and a new prohlem of the same type is generated. In the case of more complicated subject matter an alternative procedure after a specified numher of incorrect responses (anticipated or not) might he to hranch to a remedial tutorial module. Uoon com~letionof such a module the program could return td a new pioblem of the type that had caused difficulty previously. A brief illustration of how a program based on Figure 1 would interact with a student can he described in the case of the drill on symbols for elements that was mentioned earlier. Generation of the vrohlem would involve selection of a chemical iymhul, sa\. Mg,from a data flle.'l'he synlvd would he printed and the student asked to respond with t h name, ~ per-haps as shown in Figure 3. The response "magnesium" would cause the computer to print "Good" or "OK!", to flag Mg in the data file so it will not he selected again, and to present the symbol for another element. A predictable incorrect response to Mg is "manganese," which could trigger the message, "The symbol for manganese is Mn." An unauticivated resvonse minht cause the comouter to give the correci answer &thout finygina the iyml~oiin the d'& filr. The rrivonse"HeIpn mirhr dothesame thine. alrhourh for $om? symbols (those based on Latin names,-for example) clues might he given. Since only a single type of question is to he presented in this lesson, a response such as "Skip," "Back," or "Stop" can signify the end of the student-computer dialog. Courseware
Courseware refers to the instructional Droarams that make up a CAI course. Courseware is only a subsetof CAI software. Software also includes the overatina and suoewisors programs that deliver the course material, keep student records, and carry out authoring and editing functions. Lack of highquality courseware is a major factor limiting the growth of CAI, both in chemistry and in other disciplines (1).A great manv CAI . nroerams have been written. hut there are a t present no comprehensive packages that cover a semester's or a vear's work, are thoronnhlv tested and documented, and are available in format cokiatihle with the majority of existing computer systems. Programs that can he easily transported from one kind of computer system to another are usually written in general-purpose languages like BASIC, hut such languages were not designed specifically to handle sophisticated CAI strategies and may require more programming expertise. Consequently the more readily trans-
a
Repeat this problem or
Figure 2. A possible CAI branching strategy.
Volume 56. Number 4. April 1979 / 221
...some students who are embarassed to show their "ignorance" to a teacher or tutor are willing to do so to a computer. portable the program the less representative it is of stateof-the-art CAI, and, in many instances, the less likely it will be sufficiently sophisticated to serve as an effective learning tool. Designing and producing high-quality courseware is a slow, tedious process. A full-time commitment of several years will produce only enough material to support a one-semester course, and a t least as much effort is required to develop a major courseware package as to write a textbook. The primary skill required is experience in working with students and coping with their difficulties. Computer programming ability is much less important, especially when a programming language specifically designed for CAI is used or programming assistance is available. The CAI author must devote a great deal of time to altering and augmenting operational programs on the basis of experience gained as students interact with the programs. This process is never completed and has a half life of a t least one year, so it requires a long-term commitment. As in the case of textbooks, a small number of skilled authors probably will write most of the best CAI programs, but many teachers will prefer their own materials even if of lower sonhistication. An important feature of CAI that distinguishes it from most other instructional methods is the canahilitv it nrovides for continually making incremental improvements in course material. sometimes even while students are usine a lesson. A CAI proxram can and st~oulde\,ol\e as experience is gninrd and ;idditimnl need.; are r)erwivt:d. Such growth is onlv 0 0 9 sible if adequate means are provided forcollecting data on student interactions with a program. Unanticipated responses to questions are most important. These are often Himple typing errors, hut occasionally they can reveal patterns of thought, conceptual difficulties, or simple pitfalls that would otherwise not occur to the author. These usually merit special treatment in a program. A simple example from our experience is naming a hydrocarbon "septane" instead of heptane; the student was wrone here onlv in detail. not in concept. . , and should be so informe;. More elaborate data collection is reauired durine the initial development of all but the simplest CAI This should include the number of students who start and who successfully complete a lesson, the frequency with which each anticipated response to each question is selected, the time spenton each question and each lesson by each student, and, when randomly selected parameters are involved, a record of the question itself. Analysis of this kind of information provides the basis for improving the lesson. For example, a look of interaction mav reveal a t response Datterns and the leneths " that one or two questions in a lesson are harder or easier than the lesson desiener expected. Reorderine the auestions or modifying them to fit better into the flow of the lesson can then follow. On a broader scale, results obtained after thousands of students have used a CAI lesson provide statistically meaningful data for that particular group of students. This more accurate view of the specific pitfalls encountered by chemistry students should be of considerable value to lecturers and textbook authors, as well as to CAI lesson designers.
" .
Authoring Languages and Systems
In orinci~le. . . the ooerations that are most fundamental to CAI can be expressed in nearly any programming language. In practice. however. com~utationallaneuaees like BASIC. F O ~ Y I ' R A Nand , API. do not lend then~selv&readily lo the desien and oraanizatim of any but the smallest and simolest ~ ~ f i e s s o nAs s . we have already mentioned, a CAI program must be able to interpret student responses, branch appropriately based on such responses, and perform a number of other specialized operations over and over. Coding these 222 / Journal of ChemicalEducation
procedures in a general-purpose language consumes a great deal of an author's time in routine, repetitive work. Consequently, specialized, high-level CAI authoring languages have been developed to furnish an organizational framework upon which an instructional dialog can be constructed with a minimum of attention to non-instructional details. At present there is no standard CAI language that, like BASIC or FORTRAN, is available on nearly every computer system. A recent compilation (I) lists some 76 authoring languages, many of which are integral parts of CAI systems that include supervisory software-and record-keeping and editing subsystems. The most widespread of these is IBM's Coursewriter 111. which can be implemented on IBM and ~ e w l e t t - ~ a c k a 3000 r d series comp;ters and is now obsolescent. The best of the widelv known laneuaees is TUTOR ( 2 ) . which is closely tied to thedesign of the P ~ A T O CAI system and requires a large Control Data Corporation computer. Some languages, like PILOT 73, are simple enough to run on nearly any nmputer but they tend lo lw t ~ simple r tosupport exrmsier C A I pn>ject. I n Canada a National Authoring I.ai~guaoe,N.iT.4.L-7 1, has 11wndeveloped, but it is too son11 to tell whether it will become widely used. It is difficult to lay down rigid requirements for CAI authoring languages, or to give specifications for an ideal language. People can generally work with whatever facilities they have, but one would like to have the organization and clarity of ALGOL, the string handling and pattern matching of SNOBOL, and the computational elegance of APGtogether with the graphics facilities of TUTOR. There is no reason in principle why these attributes could not be combined into a practical, generally available CAI authoring language, but it will probably be a while before such a language becomes a reality. In the following paragraphs we summarize the important features that should be considered when evaluating an authoring language. The table on pages 224 and 225 presents an evaluation of several laneuaees used for CAI..based on these features. It should be egphasized that the attributes "powerful.""moderate." etc. that aonear in the table refer not onlv to what the lang"age can do,-but to the ease with which thk particular feature can be coded in the language. Thus "powerful" usually means that the feature can be invoked by use of a single command, "moderate" means that some s ~ e c i a l programming is required, and "wt!ak" indicates that will he preferable to rmc that does nor when graphics tern~inalsoecomr more r~adilyavailable. R(vr)rdrny r.f Studenr Hesponsr.,. We haw already mentioned the importance of analyzing stlldenr responses as inn aid to coursew:in, drv~lopmenr.Most CAI languages provide ior thii auromaticallv whilt. some require special progmmming. Some C:\l systems also pnwidr for rwording of studrnt commtmts to thr author. A related feature is the capnhility of recording the point tit which a student stopped in tht. program, so that the course can be resumed a t a later session: Documentation. Most CAI programs require continual revision and debugging as more experience is gained from student-computer interactions. Such revision is facilitated greatly if a source-code program listing clearly specifies the algorithm used by the original programmer. Some languages are inherently clear and easy to read. Others achieve claritv when comment lines are int&spersedliberally among execitahle program statements. Such documentation is essential to prevent the sad hut common phenomenon of the program that has to he entirely rewritten because nobody (not even the original author) can remember or understand the algorithm. Availability of Chemistry Courseware. The tahle indicates the names of some persons who have sizable collections of CAI materials in cbemistrv. The existence of a bodv of usable courseware ne6.d not be the determining factor in st:lecring a CAI lan~uazeur svstem, howwer. It is ~lsuallvstraiehtiorwilrd to writea Gogram that translates CAI matkrials From a less powerful to a more powerful CAI language. Automated . . translation between l&unycs of comp;mt~lv~ < A Y P I ic also poidith, alth~ughmore human intenention is needrd in such cases. Coursewriter materials have been machine-translated into several other languages, BASIC programs have been converted to COMMON PILOT, and even TUTOR (nongraphic) has been hand-translated into a number of other languages to demonstrate the feasibility of automated translation. Current information on translation services and programs usually can he obtained from the major users of any particular language. CAI Terminals
The terminal is the principal communication link between a student i n d a CAI course, and the capabilities of the terminal define and limit the sophistication of the CAI that can he delivered. So far the CAI market has not been large enough to promote commercial development of terminals specifically designed for CAI, hut advances in technology and demands from business users for more sophistication seem certain to bring- terminals that are adeauate for CAI into an affordable price range very soon. The authors do not entirely agree on the minin?um requirements for a CAI terminal. Some of us feel strongly that devices such as Teletype printers, which are limited to upper Volume 56, Number 4, A ~ r f l1979 1 223
Comparison of Features of Some Commonly Used CAI Languagesa
LANGUAGE
COURSEWRITER ill IBM Program Product for Systeml360; also available an HP 3000
Who has developed chemistry materials?
S. Lower. Simon Fraser Univ.
Language Structure
Linear, global variables only, good implicit branching, moderate use of GOTOS.
Accessing Data Lists
limited and com~licated
Extended BASIC (may not be applicable to all microcomputer implementations) J. J. Lagowski. G.
Culp. Univ. of Texas; many others Subroutines. often no local variables: no implicit branching; moderate use af GOTOs; (Language Structure varies from one implementationto another.) unlimited but com~lex
TUTOR The PLAT0 authoring language developed at Univ. of iilinois
APL Originated by IBM. now more generally available.
Common PILOT Developed at Western Washington Univ.
S. Smith. Univ. of Illinois
D. Macero. Syracuse Univ.
G. Gerhoid, Western Washington Univ.
Efficient block SlrUCtUre, but no local variables: good implicit branching and powerful CASE CO~SBUC~S.
Procedure blocks with locsl and global variables; implicit branchingdifficult to simulate.
Subroutines, no local variables; some implicit branching, moderate use of GOT05 but minimized by Convenient conditional specification. unlimited. moderately com~lex
unlimited and flexible: moderately comolex.
varies with implementation. but can always use arrays I ) powerful but inefficient, requires complex Subroutines 2) powerful
2) moderate
1) powerful
1) moderate
2) extremely powerful
2) powerful
1) moderate computation required 2) by ~ubroutinecall
Character Data I ) answer judging
1) powerful
1) requires complex Subroutine$or System functions
1) powerful
2) manipulation
2) very weak
2) Moderate-weak (good with System functions)
2) powerful
Numeric Data I ) answer judging
1) very weak
I ) moderate: requires Computation
2) integers only in most versions
2) powerful
1) powerful: includes algebraic expressions and dimensions 2) powerful: includes bit and byte manipulations
I ) awkward and limited
1) computation required
7) powerful and easy
1) powerful and easy
2) by subroutine call or CHAIN statement
2) by module call or CASE statement
2) by function call or array reference
large number, re~trictednames. dimensioning required
large number of predefined types, may be flexibly renamed
unlimited number, no dimensioning or Specification required
large number. restricted names. dimensioning required
by BASIC functions
by function modules. but less necessary owing to large number of commands extremely powerful
convenient, by use of APL functions
by BASIC-like functions
2) computation
Random Selection 1) numbers
2) Text and modules
Variables and Data Types
Extensibility
Graphics
limited number, predefined names, no floating point (Can access BASIC on HP 3000) difficult: requires assembly language functions. (Can access BASIC an HP 3000)
none
none, except in
none
spacial dialects Recording of Student Responses
Documentation I ) intelligibility of listings 2) commenting Major Virtues
Maior Drawbacks
1) powerful
moderate; point. vector, and character graphics by user-constructed utility programs
automatic
by user-constructed utility programs
by user-constr~cted utility programs if file inputloutput is available
1) poor-fair
1) poor
1) hopeless
2) fair large quantity of Courseware, vendor support, easy to learn
2) fair widely available, well known
2) g w d quality and amount of courseware, ease of using
2) fair computational elegance. availability
2) fair IoW-COSt miCrOprOCeSSOr implementations ease of learning
cost, inefficiency and ObsoIescence: limited computational facility
difficulty in programming, too many dialects
cost of system or CDC PLATO service
System limitations on ease of programming
limited number of function$ and author conveniences
"Theauthwsacknowledge Gw cwperation and helpot: AlfredBa*. University of Caliirxnia. Irvine; George Culp. University ot Texas. Austin: Hany Keller. Digital tquipmen Corporation; and Taylor Pohlmsn, Hewlen-PacLard Corp. in Providing infamationIncluded in this table. One mior CAI system. the TlCClT project, has not been described here because it includes no chemistry coum=%are and aner some effort the auihore were unable m obtain the iniwmtion required for the kbla.
224 1 Joumal of Chemical Education
IDF Instructional Dialog Facility marketed by Hewlen-Packard wrinen in BASIC
IPS Course design and documentation language under development at Simon Fraser Univ.
DIALOG CAI support system an SIGMA 7 at Univ. of California, lrvine
CATALYSTJPIL Available from Univ. of Pittsburgh for DEC system10
PASCALIDIALOG Under development Using Univ. of Calif., San Diego PASCAL None yet (A. Bork Univ. of Calif.. Irvine) PASCAL is a Structured language With procedure blocks and full Control Structure.
DECAL DEC author language marketed by Digital Equipment Corp.
K. Gregg. Vancouver Comm. College; and others Subroutines, no local variables (except 12 counters), g w d implicit branching.
S. Lower. Simon FraSer Univ.
A. Bork. Univ. of California, twine
K. J. Johnson. Univ. of Pinsburgh
Procedure blocks with lmal and global variables, good Implicit branching and conditional modifiers with CASE constructs.
About 200 assembly language macro calls: FORTRAN s~broutines.APLbased screen design capabilities
Linear, subroutines allowed, global variables except With subroutines, good implicit branchingand CASE constructs.
moderately complex
easily done using DATA modules and GETDATA commands
requires programming skill with macros: can use FORTRAN arrays.
unlimited, but requires indexing
unlimited
1) moderate
1) powerful
1) powerful
1) powerful
1) powerful
21 weak
2) powerful
2) powerful
2) powerful
2) powerful
1) moderate: requires computation
1) powerful
1) powerful
1) powerful
1) powerful
1) tolerance and ranges may be specified.
2) powerful
2) powerful: uses APL primitives
2) powerful
2) powerful
2) powerful
2) powerful
difficult
1) powerful
1) powerful
1) powerful
1) powerfvl
1) computation required
2) by subroutine call or CASE statement unlimited number, no dimensioning or specifications required
2) powerful
2) powerful
2) powerful
unlimited number and names
unlimited number, no dimensioning or specification required
2) by branch random statement (similar to CASE) similar to BASIC
by BASIC functions
by functions in command language, similar to APL
difficult except by preparing new assembly language macros
by PIL functions (PIL is an interpreter like BASIC, but more powerful)
new procedures easy to prepare
difficvlt: requires alteration of BASIC program
none
not yet implemented
powerful
none
good, including limited animation
none
automatic; integrated with HP Instructional Management Facility
automatic
at author's discretion
automatic
at author's discretion
automatic
limited number.. ,oredefined but can access BASIC
unlimited
1) fair
Segmented structure with ordered blocks within segments. Optional branches.
1) fair
2) fair availability on H-P sy5tems. ease of programming in authorprompting mode
2) g w d flexibility and power. efficiency in programmingand documenting
2) fair graphics capability and computational power
2) variable two languages In one: CATALYST a CAIauthor language. PIL an excellent interpreter
2) good Powerful language becoming widely used. Available on many microcomputers.
2) not available interactive programming in author made; easy to learn and use
limited programming options and flexibility
lack of general availability; requires other systems for support
several languages needed
limited availability; wrinen in assembly language for the DEC-systemlo
Sophisticated language to learn.
lack of flexibility, graphics. extensibility, and courseware
Volume 56, Number 4, April 1079 1 225
Lookinginto the future, we see the microcomputer as a major factor in the next stage of CAI development. case characters only, are not capable of viable CAI, except perhaps for very limited, simple applications. Others of us have written and/or used programs designed for presentation on hard-copy or cathode-;ay>uhe terminals that are limited to upper case. This latter group, while coanizant of the advantages of a CRT terminal that can handle lower case characters, believes that potential CAI authors should not he discouraged simply l~ecausrthey are locked into an all upper case environment. I n any case there are several additional featurcs that are needed if a terminal 1s tu deliver statr-nfthe-art CAI. These are discussed in the next few paragraphs. Random-Access Write/Erose. The ability to write and erase any section of a screen display without disturbing other areas makes it possible to add extra help where needed and later erase the comments so that the completed display represents a coherent development of some concept. Supplementary Character Set. It is often convenient to define and use rnecial characters in addition to those orovided hv the standard
writelerase, the ability to design your own characters simplifies the presentation of animated graphics. Experience has shown that animations help students to visualize coneepb such as reaction meehanisms. Touch Resoonse. A touch-sensitive vanel. which tells the comvuter khich what. nreaof ihe dis~lav ~, , Screen is heinb touched. ar a liehtven. .. . servrsthr snrnefunct~cm,sllousthear~~dent t o pumt tr~thescrecnin reiyonsc to .a quest~ot~. Th!; :reatIv incruses the rase nntl sprrd oi student-computer interactions, especially for students who do not type well. Graphics. The ahility to draw a graph in response to user-selected parameters adds greatly to the richness of CAI. For example,students can be asked to interpret nmr spectragenerated from data supplied hv an instructor. or students can exoeriment with counline constants and chemicalshifts. eeneratine thdir own soeetra toe&afeelfor the ~~~
point to a graph, drawing, or chemical structure instead of having to devise a verbal response that describes a visual stimulus. External Interface. It is often useful to present information from slide projectors, audio devices, videodisks, or other computer-controlled devices. This requires an interface between the CAI terminal and the external device. A great many computer terminals are currently on the market over a wide range of prices. Space restrictions prevent us from providing any meaningful evaluation on a specific, terminal-by-terminal basis, and such an evaluation would probably he unwise anyway because of rapid technological developments in this area. Terminals that handle lower- as characters. cursor control (comouterwell as u~ner-case .. controlled positioning of characters on a display scree;), and limited graphics are widely availahle in the United States a t prices from $700 to $1500. Low-cost ($3000-$6000) graphics terminals, such as those availahle from Hewlett-Packard and Tektronix, have most of the features desired for CAI. Terminals offering all of the state-of-the-art features listed above may be expecied to cost $6000-$8000. An overview of what kinds of terminals are availahle can be obtained by scanning advertisements in Datamation, Computer Design, Byte, Kilobaud, and/or other periodicals oriented toward computer hardware. Specific details can then he obtained from individual manufacturers of terminals. Cost-Benefit Analysis of CAI
Costs and benefits of CAI depend strongly on what type of CAI system is implemented, and for a given system conclusions about costs and benefits also depend on numerous assumptions, all of which seem to interact (3).For example, CAI 226 1 Journal of Chemical Education
can sometimes he implemented to a limited extent on an existing computer .;\.item nithour ('xper~ditt~re of mure than 3 fw thuuiand dollars. In such a situation cosrs of' s\.strm hardware, system software, and perhaps telecommunickions are usually absorbed by the computer center and assumed to be negligible by a CAI user. The main costs are operating charges for running CAI programs and time devoted to develooine courseware. For small o~eratioosthe latter is often d o n k e i h y enthusiastic faculty and programmers, and costs are small enough that little or no formal justification in terms of benefits is needed. On the other hand, a large CAI system designed to handle a variety of disciplines, manv authors and courses, and enough students so that a major fraction of instruction is computer-assisted may require capital investment of millions of dollars as well as sizable continuing costs. In this case system hardware, system software, telecommunications, operating, and courseware-development costs are sure to he included on the balance sheet, and explicit identification of benefits becomes a necessitv Although nonusers often assert that CAI leads to depersonalized and alienated students, instructional experience shows just the opposite. Students appreciate immediate feedback on their work and the opportunity to work a t their own paces and a t times convenient to them, and they are enthusiastic supporters of high-quality lessons. CAI aids instructors in identifying students who need special help, and, because it relieves teachers of the need to cover routine material, CAI makes availahle time to provide such help. Also, a CAI-based course can be completed in as much as 30% less time than a conventional course. a factor that nermits accommodation of additional subject matter within'the same number of class hours. Finallv. . . CAI users find that thev can exnect a much larger iraction aritheir students to master a gi\,en skill or set of'skill-:than is ~ r a r t ~ cIn n l cunventional means. R I cxamnle. ~ . . it i- rrnionahle t o ins~;t that oil metnhers of n class he o l h to nssign oxidation numbers or identil\i omiurate acid/l~asrnairs a t aproficiency level of 90%, instead of thk much lower Standard that is commonly achieved in conventional instruction. Grinlted educnt:on inrdvrs more than just acquisition o i skills, hut a11 instructor's task is wrti~inlvmuch casirr if'unifurmitv grf background and preparation can ht: asiumed. The benefit.; of' CAI listed in the previoui paragraph donot arcrtlr autotnaticnllv when 3 C.\l sviten~is madv availahle. Each instructor muit understand what CAI can and cannot do, adiustments must be made in instructional stvle to accommbdate the new mix of learning experiences CAI brings, and CAI must he adapted to each institution's faculty, students, and facilities. If these factors are ignored, CAI may have little demonstrable advantage (4). The Crystal Ball
Collectively the authors of this article span a wide spectrum of experience with CAI systems and applications. This ranges fromework with large numbers of students using the most powerful hardware available and hacked by significant administrative and technical suoaort. a~nlications .. . throueh " .. hased on an existing main-campus computer and involving varvine of s u.. ~~ort - numbers of students and varvine . -quantities . (or opposition), to work with significant numbers of students usine dedicated small comnuters where minimum cost was of top prior~tv.Dwpite this diversity otexperience, our cnnclusims regarding CAI are surprisingly similar.
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The skill and commitment of the author-as-teacher is the most important component of good CAI. CAI materials must be continually tested and, on the basis of that testing, rewritten. The quality of CAI materials is ultimately dependent on the suitability of the authoring language and to a lesser extent on the capabilities of the display terminal.
