D. A. Humphreys and R. H. Tomlinson I Closed C h i t Television in

McMaster University Hamilton, Ontario

Canada ( Freshman Chemistry Laboratories

There has been increasing use of audio- visual aids in the chemistry classroom (1). Their ap- plication to the laboratory course has not received comparable attention, although one novel approach to the freshman laboratory course has been discussed (2). This paper reports on three years' experience with closed circuit television in the freshman chemistry laboratories a t McMaster University. There are several unique problems associated with the freshman chemistry lab- oratory. I t is particularly those which stem from the large numbers of students that are effectively overcome through the use of television. We have found that one staff member, using television and working with an adequate number of demonstrators, can bring a uni- formity of approach and sophistication of demonstra- tion which leads to an improved program.

Studio and Laboratory Arrangement

At any given period we operate five laboratories, each holding 32 students. In each laboratory there are two or three 24-in. monitors situated along one side approxi- mately 6 ft from the floor (Figs. 1 and 2). This ar-

Figure 1. (left1 The laboratory.

Figure 2. lbelawl The Iaborm- tory-A general view during the introductory lecture.

rangement allows easy access to thc television monitor if a closer viewing position is required. Each monitor is visible from the student's working position.

All monitors are programed from a single studio (Figs. 3 and 4). This studio is operated without any auxiliary staff. The whole system is turned on by a singlc switch and the lecturer controls the cameras, video-tape, and sound. A television monitor in the studio allows the lecturer to view the same picture as the students.

Figure 3. (left1 The studio.

Figure 4. (right1 The studio-View seen by Cl, showing C2.

Camera C1 (Fig. 3) has a wide angle lens and provides a general picture of the lecturer and demonstration bench. Camera C2 is situated on a pan-tilt head and has a zoom lens. This camera is within easy reach of the lecturer. I t is used for close-up pictures of the blackboard or details of the apparatus arranged on the demonstration bench.

A video-tape recorder, which is located underneath the display bench, is used for showing standard tech- niques (e.g., titration) and apparatus (e.g., the balance). The switch (S) which is located close to the blackboard is used to switch to either of the cameras or the video- tape recorder.

The audio system includes a talk-back arrangement. In order to maintain a personal contact with the stu- dents we have two or three demonstrators in each lab- oratory. These demonstrators or any of the students can at any time address a question to the lecturer. A microphone in each laboratory may be activated by a switch which simultaneously turns on a warning light in the studio indicating the room from which the ques- tion originates. When the microphone is used the question can be heard in every laboratory.

Purpose of the laboratory

The laboratory provides a medium for the student to develop his ability to correlate observation and explana- tion, as well as the basic manipulative skills of the experimental chemist. The aims of the laboratory course have been discussed in detail elsewhere (5-5).

Primarily, the student should be working indepen- dently and making his own discoveries. There must, however, be a balance between discovery and the blind following of instructions; otherwise, the laboratory period will become disorganized and student time will not have been efficiently spent. This implies a need for some appropriate introduction to the laboratory class and supervision during its progress.

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Introductory Lecture and Laboratory Supervision

Two main approaches, apart from the television method we are describing here, are currently used as a means of introducing lahoratory periods to large fresh- man classes. The pre-laboratory lecture is given either in a lecture theatre or in the laboratory itself. Each of these methods has advantages and disadvantages. When the introductory talk is given in a lecture theatre, there is the advantage of a uniform approach presented by one of the best-qualified instructors. On the other hand, a number of disadvantages arise. The instructor tends to talk excessively long in trying to cover every eventuality, since he knows that he will not have a fur- ther opportunity of speaking to all the students collec- tively before the end of the laboratory period. There is also a waste of the student's time in going to and from the theatre. When the introductory lecture is given in the laboratory the disadvantages of the lecture theatre approach do not apply. However, the ad- vantage of the uniform approach by a single well- qualified instructor is lost if more than one laboratory room is required. With a number of rooms, each op- erating several days a week, a separate instructor, who has to repeat the lahoratory introduction on each occasion, is required for each room. Whether the pre- laboratory lecture is given in the theatre or laboratory, a major disadvantage is the difficulty of demonstrating anything but the grosser features of an experiment to the full group. This has usually led to the compromise where the lecturer relies on blackboard illustrations, followed by direct assistance to the student from demon- strators during the experiment.

At McMaster we have had experience with both the lecture theatre and the laboratory environment for our introduction and are convinced that television com- bines the best features of both without the disad- vantages of either. The use of television retains all the time-saving advantages of instruction a t the stu- dent's laboratory bench but allows an easily visible and concise demonstration given by a single instructor, to be projected to all rooms a t one time.

The television system also allows properly-timed interjections to be made during the course of the labora- tory period. The student may be given a deliberately brief introduction so that he will have the excitement of recognizing and solving problems using his initiative and making his own discoveries. Many of the good students will quickly solve problems as they arise, but eventually a time is reached when appropriate assist- ance must he given to the remainder. There will, in fact, be less disturbance a t this time using the television system since the student's bench is near one of the monitors. The problem of the individual, of course, are best resolved through interaction with one of the several demonstrators in his laboratory.

The Use of Video-Tape

Video-tape is especially useful for demonstrating technique. It turns out to be more than a method of recording what could otherwise have been done live. It allows time-compressed sequences to be used, making possible the demonstration of just those key features needed for the development of good technique. Demon- stration of technique is especially important a t the

freshman level where large numbers of inexperienced students often pick up by intuition habits which they will later have difficulty in correcting. Video-tape allows other experts in the department, e.g., analytical specialists, to be involved more conveniently, thus en- couraging more uniformity in approach within the department. Other aspects of the experiment, where discovery, observation, and deduction are important, can be left to the student.

Freshman classes are generally large, and the student lockers contain only relatively inexpensive equipment. The experiments, which aTe designed to illustrate vari- ous principles and techniques, often yield results of limited accuracy. Using appropriate video-tape, i t is possible during the course of the laboratory to show to the students apparatus capable of more precise measure- ments. One purpose of the freshman laboratory is to give the student the opportunity to perform his own experiments complementing the lecture material of the course. There are, however, some topics, particularly relating to atomic and molecular structure, for which useful experiments cannot he performed using the usual freshman equipment. We have used an entirely video-taped experiment in which the infrared spectrum of the HCl molecule is obtained. From absorption fre- quencies which are read directly from the monitor, the student calculates the bond length and moment of inertia of this molecule. The student does not perform this experiment himself, and we therefore feel that such use of television should not he extensive. Experiments of this kind do, however, allow good illustrations of the lecture material and a t the same time give a t least one example of the use of modern instrumentation.

Whenever an experiment has an important practical application, particularly in local industry, the student's perspective can be broadened if he sees a short video- tape showing the key features of the industrial method. Using video-tape for example, we can record an iron-ore determination being carried out in the analytical lab- oratory of a steel company and use i t when the students are themselves titrating ferrous ion solutions. Such prerecorded off-location tapes take only a few minutes of the student's laboratory time, hut he sees the imme- diate application of what might otherwise seem to he a rather obscure redox titration. From the point of view of the instructor these short pre-recorded sequences present minimal production problems in view of the instant re-play and erase features of video-tape. This contrasts markedly with the problems encountered using 16mm film where long delays between shooting and viewing are common. Certainly the use of video- tape avoids the lecturer having to constantly repeat his presentation of standard techniques.

Additional Features of Closed Circuit Television The use of the closed circuit system allows the student

in a large group to see the demonstration in as much de- tail as he would in an individual demonstration. He can, for example, read the vernier on the balance or see the tip of a melting point capillary containing a single crystal. Such situations, where size normally precludes simultaneous observation by the students and the lecturer, can now he easily viewed by large num- hers, and the teacher's commentary can be properly coordinated with the scene that both he and the stu- dents view together.

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Many experiments involve inevitable waiting periods while some processes, such as refluxing or chromato- gram development, is taking place. The television sys- tem has given us increased versatility in usefully filling these periods. It is possible to briefly extend the theoretical concepts involved, outline later stages in the experiment; and again utilize all the advantages of the video-taped demonstration in these periods. Informa- tion can he left on the television screen for the student to make appropriate notes a t some convenient time during one of the waiting periods.

The relatively simple and inexpensive closed circuit televison system used in our freshman laboratories has limited us to a program in which all the students per- form the same experiment in a given period. With additional video-tape recorders this limitation may he

overcome. Color would he an advantage in some demonstrations hut with ingenuity it is possible to adequately illustrate the majority of situations in black and white. It is, however, now clear that whatever reservations may he expressed about the use of tele- vision for presentation of lectures, it has a considerable number of advantages in the teaching laboratory where large numbers of students are involved.

Literature Cited

(1) BARNARD, W. R., LAGOWSKI, J. J. AND O'CONNOR, R., J. CAEM. Enuc., 45,63 (1968).

(2) FLINTCROPT, N., WONG, E., AND PATE, B. D., C h i s t l y in Canada. 19. 47 (1967).

(3) C H E R O N ~ ~ ; N.'D., j. CHEM. EDUC., 39,102 (1962). (4) YOUNG, J., J. CAEM. EDUC., 43, 121 (1966). (5) LAYTON, M., Canadian Chemical Education, 3, 19 (1967).

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