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C H A P T E R I I

The Computer-based Teaching Machine*

C E R T A I N PRINCIPLES OF LEARNING, developed in psychological laboratories and validated in educational practice, have currently been applied with considerable success to the development of new self- instructional textbooks and teaching machines. These principles have been identified with the educational process called programmed learning.

Programmed learning is a method of self-instruction, carried out by the individual student working with a special teaching device. The teaching device displays educational material to the student. The material has been broken down into its conceptual elements, with each concept taking from twenty to forty teaching machine items for exposition. An item is simply a frame or a slide of information of one or two sentences in length, usually followed by a question.

As each student proceeds through the instructional material, which is carefully prepared (or programmed) in small easy-to-take steps, he is required to respond actively at each step by filling in a missing word or selecting a multiple-choice answer designed to test his understanding of the information in that step. As the student writes down his answer to each step, the answer is recorded. This provides a basis for revising the educational program so that it will teach better and more efficiently. The data left by studehts also provide a powerful tool for learning about human learning.

The student's response sets up a means for reinforcing or rewarding the student as he learns. The machine immediately indicates to the student whether he is right or wrong, informs him of the correct answer, and keeps a record of this and subsequent responses.

*Adapted from "Computer-based Teaching Machines," Journal o] Educational Research, June-July, 1962, p. 528-31, by D. D. Bushnell.

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12 AV COMMUNICATION REVIEW

Much of contemporary teaching machine programming has been derived from the systematic position advanced by Skinner (7), who holds that the teaching sequence should be organized to maximize successes and minimize failures. The teaching sequence for a given body of material will then necessitate a lengthy series of teaching items to be seen sequentially by all students. Every student will traverse the same sequence regardless of his previous educational experience and aptitude.

Another position on teaching machine programming is that the machine should be flexible enough to adjust itself to every student's unique abilities for learning a subject. Such a program utilizes a varying number of items and varying sequences of items. Each student will go through a teaching session seeing a sequence that best fits his ability. The student will see additional items when his errors indicate his inabilty to grasp a point or a concept. He then will be shown easier items on the same concept, which are intended to help him over the hurdle he has just met. A student who meets no hurdles will skip redundant items.

What was developed in this system was a form of "machine responsiveness" or adaptive control based upon individual student learning needs. The machine does not impose a behavior pattern on the student but seeks a compromise with the learner. First it challenges the student with moderately difficult material and cooperates with him when he needs help by presenting easier questions with more prompts. The machine adjusts the difficulty level and selects a variety of approaches to a given conceptual goal on the basis of needs of the particular student.

Machine Responsiveness to Student Learning Behavior

The potential of the computer for handling individual student differ- ences in learning rate, background, and aptitude is of primary interest to most researchers working with computer-controlled automated teaching systems. Machine responsiveness to student learning behavior can be achieved by branching the student forward, laterally, or backward through subject materials primarily on the basis of his response to con-

Figure 3. The sample history lesson in this figure was designed for a machine with decision-making capabilities. Some of the instructional items branch the student to remedial paths designed to correct part icular errors. At two points in this lesson, decisions are made on the student's cumulative error tallies. A t these points, additional instructional items are given to the student if he is experiencing difficulty in learning the material. A t the end of the lesson, a self-evaluation item is presented to students who have made at least one error. This allows the student to decide whether or not he needs more instruction

COMPUTER-BASED TEACHING MACHINE 13

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tent questions seeded throughout the instructional program (see Figure 3 for an example of a branching program).

Multiple criteria for branching is a goal in research with computer- based teaching machines, but generally, the current teaching machine will only branch for the following reasons:

1. Characteristics of student response--the promptness and/or de- finitiveness of his reply.

2. Nature of response--was it right or wrong, what specific errors were committed by the student.

3. History of student learning behavior his previous response pattern, problem areas, and reading rate.

4. Relevant student personal data--his IQ, sex, personality, apti- tudes.

5. Nature of subject matter. 6. Degree of student motivation. 7. Student-generated requests for re-routing. The term "flexibility" has two applications in connection with the

computer-based teaching system. First, the machine is capable of modi- fying its own mode of instruction during the course of a training session. Item sequence, knowledge of results, and other such variables depend on the factors cited above, as well as on the instructions programmed in the machine. It is this type of responsive self-modification which significantly distinguishes this flexible machine from the many non- computer-based teaching devices commercially available. Conceivably, this unique characteristic may lead to a major improvement over other conventional and automated instructional techniques in terms of teaching effectiveness.

A second type of flexibility, of great importance to any teaching machine intended as a research tool, pertains to the ease with which the machine's operation can be altered between training sessions. Such alterations are necessary to permit the investigation of different training procedures or machine characteristics.

The "responsive" experimental teaching machine demands a considerable degree of complexity in type of control unit which provides computer, because the computer

the machine control unit. The only the necessary flexibility is the digital is the only instrument capable of

determining the item sequence and knowledge of results to be presented to the student as well as carrying out the bookkeeping activities upon which such determinations will be based.


Inputs from the student are usually introduced by means of a typewriter keyboard connected to the computer control unit. These inputs consist of the student's responses to instructional items, or, in some cases, of requests for further information from the computer.

Two general types of stimulus material are usually presented by the computer-controlled machine to the student. The first type, consisting of the actual instructional items, can be displayed by a slide projector or TV display acting under the direction of the computer control unit. Signals from the computer control the sequence of items to be presented.

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Figure 4. Equipment diagram for PLATO II

The second type of computer-based teaching machine output consists of evaluative information concerning the student's performance on the instructional items. This information is often printed out on the page printer of the same typewriter used for student inputs.

This brief description of the essential elements of an automated teaching system controlled by the digital computer does not, of course, hold for the specific configurations of components used in the research described below. It should also be stressed that the tools of this research are of less significance than the purpose for which the tools have been


devised, a point sometimes overshadowed by the luster of the computer.

Computer-based Teaching Systems

PLATO II (Programmed Logic for Automatic Teaching Operations) [Bitzer (1) ] , is the name of a research project using an ILLIAC corn-

QUESTION: GIVE THE POSITIVE,

NON-TRIVIAL DIVISORS OF 51

IN INCREASING ORDER.

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Figure 5. Question displayed on the television screen of the PLATO II system

puter-controlled system of slides, TV display, and student response panel for simultaneously instructing two students in either mathematics or French (see Figure 4). The uniqueness of the PLATO II system lies in its input flexibility and the degree of control the student has over the sequences of educational materials he sees for study. When questioned on the content of material viewed on the TV screen, the student can transmit his answers in numerals, words, sentences, or algebraic expres- sions. The ILLIAC displays each character selected by the student in the blank space appearing with the question on the television screen as in Figure 5. By pressing a "judge" button, the student causes the computer to write either "OK" or "NO" next to his answer (see Figure 6). If he


is wrong, the student has the capability of asking for additional help to which the computer responds by selecting simpler, but related, material until the student presses the "AHA!" button and is returned to the question missed as seen in Figure 7.

PLATO II, although fashioned after the model of the human tutor, has only a limited degree of adaptability to student requests. If the additional "help" routines of three or four slides are not sufficient to clear up problem areas, the student is given the correct answer and allowed to proceed. However, richer variable routines are apparently

QUESTION; GIVE THE POSITIVE,

NON-TRIVIAL DIVISORS OF 51

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Figure 6. Question item with student answer and computer feedback

in design. Additional criteria for branching, on the basis of ( 1 ) specific errors made in a wrong response, (2) the number of wrong responses submitted for a given concept, and (3) how much help was required to complete a given item, are also being explored.

According to the announcement by the Coordinated Science Labora- tory, PLATO II will ultimately be modified to teach many students at the same time.


At Bolt, Beranek, and Newman, Inc., the PDP-1 computer has been programmed to control two typewriter stations for instruction in language vocabulary drill (see Figure 8). The computer types out a word from a set of German words. The student responds by typing a corre-

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Diagram of the teaching logic for PLATO II

sponding word in English. If the response is correct, the computer confirms its correctness, posts a hypothetical score, gives a compliment, eliminates the word from the set, and presents a new word from that set. If the student has been incorrect, the computer says "NO," moves the item to a missed set, and offers him the choice of trying again or seeing the correct answer. When the student has finally replied appro- priately, the computer posts a score, makes a suitable remark, and presents the next item in the sequence or a missed item from an earlier set (see Figure 9).

This research uses the computer to simulate only limited machine responsiveness to errors committed by students. Licklider (5), con- tends that concern with the hardware (displays, controls and procedures) is more effective in facilitating learning than adherence to certain learning principles derived from the psychological laboratories.

Dr. R. L. Chapman (3), formerly of Thompson Ramo Wooldridge,

C O M P U T E R - B A S E D T E A C H I N G M A C H I N E 19

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Good afternoon. This will be your German-Engllsh Lesson No. 4. If you are ready to start at once, please type "s." If you would like to review the procedure, please type "p."

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That's it. You did well, I'll be looking forward to the next lesson.

Figure 9. Typescript of a short illustrative lesson in which a computer plays the role of instructor in language-vocabulary drill. The student typed "O" to start the session, "S" to start the lesson, the English words (and terminating dots) in right hand column, and the abbreviations of "yes" and "no" in response to the computer's "ta" ("Do you want to try again?"). The computer typed the remainder, including scores and com- ments. The procedure is explained in the text


and now with Hughes Aircraft, has developed an auto-instructional device with a control system which is smaller and less expensive than a general-purpose computer, but which incorporates a large amount of operational flexibility (see Figure 10). This device, called MENTOR, provides both visual and auditory display capabilities for training one student at a time. The student responds through push buttons and is given immediate knowledge of results. MENTOR can branch on the basis of single questions, cumulative performance scores, or response time latency. It keeps a record of frame sequences, student responses, and student response times.

One prototype of MENTOR has been built for research. However, no research with this unit has been accomplished to date, although a long- term program of activities has been drawn up.

At the System Development Corporation, members of the Automated Education Project developed an instructional system controlled by a Bendix G-15 computer (see Figure 11). Other elements of the system were a random-access slide projector and an electric typewriter. The projector held up to six hundred 35-mm slides, with one instructional item on each slide, and could project these slides in any sequence desig- nated by the computer. The typewriter was also linked electrically to the computer. It was used by the student to respond to questions contained in the items and could also operate under computer control to type out feedback messages congratulating the student for correct responses or correcting his errors.

A control program for the Bendix computer was modified a number of times as the result of research conducted with the teaching machine. It was found, for example, that it was not feasible to use the same item both for teaching and for diagnosing student needs. Questions contained in the conventional fixed-sequence program items are heavily cued; such items are designed to maximize the probability of correct student responses, so that the student can be reinforced for the desired response behavior. These conventional "give away" questions cannot be used as criteria for branching, since they do not effectively discriminate between the student who is ready to tackle a new concept and the student who needs further work on the earlier concepts. In a revised program, soc researchers used two types of items: informational items and diagnostic items. An informational item contains a factual statement and/or pic- torial display. A diagnostic item presents a question, usually in multiple- choice format. It is a test item with plausible distractors and minimal


cues. Student responses to these diagnostic items provide a major cri- terion for branching decisions.

A lesson began by showing the student a series of moderately difficult items dealing with a particular topic or concept. Either during this series or at its conclusion, he is asked one or more questions covering the

Figure 10. The TRW Mentor automatic tutoring device


materials on this topic. If the student performs adequately on the questions, he is taken directly to a new topic. If his performance fails to meet the established criteria, he is given further work on that same topic. This work may be a review of materials already seen or a new set of materials, perhaps at a lower level of difficulty. The student is then retested, and may be taken ahead in the lesson or given still further remedial work if necessary. In this way, the bright student is allowed to advance rapidly from one topic to another, while the slower student is given as much remedial exercise as he may require to reach the desired level of knowledge. The G-15 keeps records of student responses and other relevant data during the lesson.

In 1961, soc constructed an experimental Computer-based Labora- tory for Automated School Systems (CLASS). CLASS permits research on the use of modern data-processing equipment not only for instruction, but also for other important educational activities such as counseling, class assignment scheduling, and the storage and processing of student and fiscal records. CLASS will be discussed more extensively in Chapter V.

W. R. Uttal (1961), at the IBM Research Center in New York, has used the model of conversational interaction between the student and his tutor for developing a computer program. The IBM 650 RAMAC system is the research vehicle (see Figure 12). In general, the interaction between the student and the teaching machine proceeds in the following manner:

1. The word, formula, or phrase to be encoded or learned is presented to the student. According to his record of experiences with this problem, it may appear with appropriate cues.

2. The student keys his response into the keyboard. When he has released all keys, the information is entered into the computer (see Figure 13).

3. The computer evaluates his answer and indicates whether he was correct or incorrect.

4. A new item is presented to the student or the same item is re- peated. Either contingency is determined by the branching logic in the computer.

5. After a number of these items are presented, a lesson is considered complete and the student is queried to determine if he wants to continue. During that inquiry, the computer is assembling a new set of items from the list of new problems or from the list of problems which have been

24 AV C O M M U N I C A T I O N R E V I E W

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answered correctly as well as items from the error buckets (a set of memory locations which store the addresses of items which have been missed a given number of times.)

Dr. Uttal feels, however, that a satisfactory theoretical and experimental foundation for teaching machines may not be laid down until computer-based instructional systems are an accomplished fact in real school systems.

At Carnegie Institute of Technology [Perlis (6)] , students are learning to program a computer as well as a machine simulated on it through an algebraic and list-processing language. In the study of computer organizations, students are informed by text and problems stored within the computer of the nature of this organization and how it relates to that of a simulated machine. Their progress in understanding is meas- ured by programs within the computer, which compare the student's answers to those of previously provided standards.

Through the simulation of the machine on a machine, the general

Figure 12. The IBM 650 RAMAC system used by Dr. Uttal for research


properties of programming are explained. Each property is described by text, tested by problems, and graded for understanding by the computer.

Figure 13. Special input/output device used for self-instruction in steno-typing. This unit is controlled by the IBM 650

According to Dr. Perlis, the purpose of this ongoing programming course is to describe certain programming principles: parametrization of processes, iteration and cycles, recursion, operational procedures of definition, representations and languages, mechanical communication between processes, and simulation.

R. D. Smallwood, formerly at MIT, has reported on an instructional program for a computer that enables the unit not only to adapt its presentation of the material to the needs of the student, but also to learn which adaptation is likely to be the most beneficial to the student. Just as the human instructor alters his presentation from year to year on the basis of experience gathered in previous presentations, Mr. Smallwood's program gives the computer a decision structure for evalu- ating the entire response history of the student, and comparing it with the response histories of former students. The computer can then evalu-

C O M P U T E R - B A S E D T E A C H I N G M A C H I N E 27

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ate the probabilities that certain branches of the instructional program will substantially aid an individual student, and choose the branch with the highest degree of potential benefit to him.

The instructional program was run on the IBM 709 computer at the MIa" Computation Center (see Figure 14). A microfilm reader was used as the output unit and the student indicated his responses on an electric typewriter keyboard. An array of information blocks was stored on the microfilm reader, and the computer was programmed to select the sequence of frames to be shown the student. The system has been applied in the instruction of graduate students in a course in pure mathematics.

REFERENCES

1. Bitzer, D. L., Braunfeld, P. G., and Lichtenberger, W. W. "PLATO II: A Multiple- Student, Computer-Controlled, Automatic Teaching Device." In Programmed Learn- ing and Computer-Based Instruction. Coulson, J. E., editor. New York: John Wiley and Sons, Inc., 1962.

2. Bushnell, D. D. "Computers in the Classroom." Data Processing, April 1962. 3. Chapman, R. L., and Carpenter, J. T. "Computer Techniques in Instruction." In

Programmed Learning and Computer-Based Instruction. Coulson, J. E., editor. New York: John Wiley and Sons, Inc., 1962.

4. Coulson, J. E., editor. Programmed Learning and Computer-Based Instruction. Pro- ceedings of the conference on the Application of Digital Computers to Automated Instruction co-sponsored by Office of Naval Research and the System Development Corporation, Washington, D.C., October 1961. New York: John Wiley and Sons, Inc., 1962.

5. Licklider, J. C. R. "Preliminary Experiments in Computer-Aided Teaching Ma- chines. In Programmed Learning and Computer-Based Instruction. Coulson, J. E., editor. New York: John Wiley and Sons, Inc., 1962.

6. Perlis, A. From a paper presented at the conference on the Application of Digital Computers to Automated Instruction, Washington, D. C., October 1961.

7. Skinner, B. F. "Teaching Machines." Science, October 24, 1958. p. 969-77. 8. Smallwood, R. D. "Automated Instruction Decision System." ScD. Thesis, Electrical

Engineering Department, Massachusetts Institute of Technology, Cambridge, Mass., 1961.

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