the computer-based teaching machine

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    The Computer-based Teaching Machine*

    CERTAIN 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 mate- rial has been broken down into its conceptual elements, with each con- cept 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.



    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 ma- chine 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 respon- siveness" 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 ma- chine 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 teach- ing 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 particular errors. At two points in this lesson, deci- sions are made on the student's cumulative error tallies. At these points, additional instructional items are given to the student if he is experiencing difficulty in learning the material. At 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



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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 pat- tern, 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 teach- ing 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 con- siderable 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 type- writer 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 teach- ing 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-




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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 answe


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