Teaching

The following is an account by David Betts and Alan Walton of how they taught the course Structure and Properties of Matter, taught to all science students in the 1960s.

• history.phys.susx.ac.uk/File:SPM_(edited_version).doc  (link to article below)
  

Preamble (Alan J. Walton and David S. Betts)
This article below, starting with the Introduction, is based almost entirely on a publication we prepared for the Institute of Physics journal Physics Education, the original reference beingPhys. Ed. 5, 321-325 (1970). We are grateful for having the permission of the Institute to make a very few minor additions or clarifications for the benefit of readers 40 years on. The style, though, can probably be recognised as belonging to late 60s Sussex. The original idea of a course syllabus designed by physicists for first-year students from a wide range of science subjects was introduced by Professor Roger Blin-Stoyle, one of the founders of Sussex as a new university taking in its first science students in 1962 (see reference below). The present article relates only to the period 1969-71, when both authors were Lecturers in Physics at Sussex University.

Introduction
Despite governmental noises about widening the student/staff ratio the two of us have recently delivered, jointly, the opening set of lectures in a two term course for first year science students at the University of Sussex. We have been sufficiently encouraged by the results of this two-man act to wish to suggest that, at least occasionally, a technique from the music hall may be applied in our universities. But first a word on the history of the course.
At Sussex, all first year students, except those studying biology, take a common course entitled The Structure and Properties of Matter (SPM), which is intended to occupy roughly one third of a students time throughout his first two terms. Although the syllabus has undergone numerous changes almost every year since its inception in 1962, its aim still remains to place the accent on understanding the structure and properties of matter in terms of fundamental atomic concepts, and further the course is planned to virtually shock the undergraduate into an enquiring frame of mind (Professor R J Blin-Stoyle 1964). But having stated this ideal the prosaic fact remains that, being a common course, there will be some students without so much as O level chemistry, and others will have opted out of doing mechanics at school. Therefore, before tackling the microscopic, it is essential to revise and re-present the behaviour of the macroscopic. Since by no means all of this material would be new to all students all of the time there is need to carry the enthusiasm of the individual student over patches with which he is familiar (or thinks he is). It was these foundations which were our main concern. As the course blossomed into atomic structure, molecular bonding, phase equilibria and so on, faculty from other schools took over the reins. Because of the wide spread in the students background knowledge and because of their often deep seated antagonism to different subjects, as for example the mathematicians attitude to chemistry, such a course almost demands an unorthodox approach if it is to stand any chance of succeeding.
There is a further limitation. The university does not have a lecture theatre large enough to accommodate the whole audience (381 in 1969). Rather than adopt the simple solution of repeating the lectures we made use of the facilities offered by the university’s Centre for Educational Technology who televised the lecture live to an adjoining theatre where it was projected on to a large screen using Eidophor equipment. However, as will be explained shortly, television was not restricted to an overflow role.

Planning - the emergence of the double act
The SPM course began early in October. Some months prior to this, David Betts was asked to prepare the foundation lectures covering Newtonian dynamics, electromagnetism, vibrations and waves, and probability theory. This part of the syllabus was new to the course that year. Not only would the precise contents have to be closely thought out, bearing in mind the students half familiarity, but it was also clear that a heavy reliance on practical demonstrations would be desirable, particularly in view of the limited laboratory time available to each student. The provision of appropriate demonstrations was basically Alan Walton’s responsibility.
So we started our separate tasks: David reading relevant material and compiling notes, Alan tinkering about in the preparation room. If a collaboration was thought of it was only in the rather rudimentary sense of assigning time for a particular illustrative demonstration. Before many weeks had passed it had become evident that demonstrations could not be properly planned out of context any more than lecture notes could be compiled without knowing what knobs would be twiddled and when. These areas of overlap would have to be talked through, and even rehearsed, together. Furthermore since both of us would be present in the lecture theatre why not employ dialogue? Why not even interrupt each other as an aid to clarifying or reinforcing the subject? This idea, once formed, rapidly began to crystallize. Indeed at times we had sternly to remind ourselves that we were not Morecambe and Wise planning next seasons show for the Palace Pier, but merely Betts and Walton preparing next terms SPM course for Sussex University. We anticipated that there should be periods where one of us would steal the limelight while the other retreated to the stalls contenting himself with the occasional verbal tomato.
There is another aspect to all of this television. We have already said that its main function was to trans¬mit the lecture to another theatre. But could we put this facility to more positive use? Should demonstra¬tion apparatus be planned bearing the capability of a zoom lens in mind? Could the impact of the dialogue not be enhanced by having two cameras and a bit of editing? At other times one camera could concentrate on the blackboard, the other on the demonstrations. Then how about introducing videotape material? We had two audiences to consider; the first watching the lecture live, the second viewing a 10ft x 15ft screen. The live audience (about 250), able to watch both lecturers at once, would have to do their own editing of the dialogue, but how would they cope with demonstrations? Those at the back of the class would find it difficult, if not impossible, to see smaller objects such as springs or meter scales. We got over this difficulty by having television monitors in the live theatre, fed continuously from the cameras. In practice the monitors were fed with the same edited signal that was transmitted to the Eidophor projector. This we feel was not an ideal arrangement; monitors are probably best switched off when not showing close ups of demonstration apparatus. Other shots, such as head and shoulder ones, can be very distracting to the live audience. There was no real problem with over¬head and slide projection as the cameras could take the projected image directly. However, because of the low light intensities in film and film loop projectors, their images did not transfer well, so these sources were videotaped in advance and piped, when required, to the monitors in one theatre and to the Eidophor in the other. It goes almost without saying that such television coverage demands a producer who apart from being able to select appropriate shots must also be able to give meaningful directions to the camera operators. In our case we were fortunate in having a one time physicist, John Field, as producer-cum-director. Figure 1 summarizes the details of the television coverage.

Delivery
At the planning stage, when the double act was taking shape, we decided on the broad division of activities in the lecture theatre; David Betts theory, Alan Walton experiment. The division was partly deter¬mined by the history of the situation and partly by personality differences which we decided to exploit (David Betts the straight man, the pure academic; Alan Walton the village idiot, pure and simple). So, broadly speaking, David would handle all the logic, would extract what sense he could from Alan’s meanderings, and summarize it carefully on the board in a pre-planned manner. He would show the real life scientist; selecting the data, analysing it, and making formal generalizations. Alan, besides carrying out most of the experiments, would make rude noises and ask embarrassing questions, the sort of questions modesty prevents the audience from asking. As the works spanner thrower he would attempt to make the audience think! Together we would inspect each others’ dirty linen and then wash it publicly. If nothing else we might convince them that physics is fun.
Before the course started we were both more than a little hazy about how it would work out. We had spent a good deal of time chewing things over, airing our linen one might say, and although lecture notes existed, detailed scripts did not. What scripts did exist contained only the crucial points and the changeover cues arrived at in talking through the lecture a day or two before. We did not rehearse formally, simply because we both felt that the whole approach leaned heavily on audience response and neither of us felt able to perform uninhibitedly without an audience. To be frank we did hold rehearsals but we felt such twits that they were soon abandoned.
The plan for the first half of the first lecture, on Newton’s laws of motion is shown in the table below. The reader will see that it is little more than a series of reminders of particular points to be emphasized either from the demonstrations or in the notes. Indeed it is not self-explanatory and it's reproduced solely to titillate his imagination.

Time Man   Topic (cues in italic)
9.00  DSB    Introduction . . .‘Isaac Newton was interested in moving objects long ago’.
        AJW    The story begins when he was six .. . First law demonstration with engine, then puck ... ‘So with no forces present, the puck moves at constant speed’.
        DSB    ‘So I can generalise . . . (pauses) but is it true with any kind of object?’.
        AJW    ‘Let’s try this cauliflower (slide) or this cabbage. – ‘So it is true’
        DSB    ‘That’s really only a definition of zero force . . . let’s deliberately apply a force to the puck’.
9.15  AJW    ‘But how? . . . (spring demonstration. Obtains slide) . . . so when F is constant acceleration is constant’.
        DSB    Writes up conclusions. ‘What happens if you use two pucks?’
        AJW    ‘halves the acceleration’
        DSB    ‘How about two springs?’
        AJW    (Claims) ‘doubles the acceleration’.
        DSB    ‘I want to see some proof’.
        AJW    Produces slide and explains.
        DSB    OK! It seems that F=Cmdv/dt. What about r=Cd(mv)/dt? . . . Would predict that F= C(mdv/dt + vdm/dt). If F= 0 and we increase the mass of, say, a puck by pouring                       water into a beaker carried on it, the velocity should fall
9.30  AJW    Let’s try it

As we gained in confidence the lecture plans grew less detailed. The necessity to be flexible was brought home to us after watching a videotape of one of our lectures which showed us both simultaneously turning over the pages of our scripts and, after a long delay, uttering the profound remark: Good, about something very trite. So we came to rely more on spontaneous reactions. Occasionally this led to timing difficulties but we quickly evolved the principle that if a non-crucial topic had to be omitted for reasons of timing, it would be omitted altogether and not merely be pushed into the beginning of the next lecture. Thus timing errors were not propagated through the entire course.
The demonstrations we employed fell into three broad categories. Firstly there were simple objects used merely to illustrate points in an amusing way. When Alan referred to Newton’s (fictitious) childhood experiences in pushing objects around, he used a toy engine. When David wished to suggest that atoms pushed closer together repel one another, he used two giant cotton wool balls. When we established theoretically that momentum should be conserved in collisions we threw pounds of butter at the wall and had an argument. When we were talking about fields we climbed a step ladder and dropped flower pots. When David wished to introduce a quasiparticle field model he borrowed his (reluctant) wife’s hair spray. Such objects as the engine, the butter, and the flowers were introduced as visual reinforcement of verbal statements. Apart from steep dry-cleaning bills and accountants who disbelieve one’s claims on petty cash, the only real danger is that the audience will become so conditioned that by next year we will have escalated to juggling with flower pots while cycling across a high rope.
The second sort of demonstration was the thought experiment which worked! In these we ‘fiddled’ things, and did so very obviously, to obtain observable results. An example: in talking about energy transfer we wished to see if there was any plausible way of combining the force which appears when energy is transferred in mechanical processes, with the distance it moves. After feigning hunger, Alan devoured one Smartie and discovered that this feast enabled him to pull a load along the bench. The pull was constant, as shown on Newton balance, and this one Smartie enabled him to move the load by 0.3m. More feigned hunger, a second Smartie, and he managed to pull it a further 0.3 m. From this David, who was by the board, noted down that Smartie consumption is proportional to distance pulled, with a constant force. At David’s suggestion we made the load now twice as hard to pull and Alan found he now required twice as many Smarties to pull it a given distance. Three times as hard required three times as many Smarties and so on. Again David wrote these conclusions up. To his query about where had the Smarties’ energy gone to, Alan produced eggs which he fried on the bench; David being quick to note that the number of eggs fried, itself a measure of the energy transferred, was proportional to the number of Smarties consumed and, therefore, proportional to the product of the force and the distance. Now of course such an experiment could, indeed maybe should, have been done using say a petrol engine fitted with a calibrated tank. Naturally all the audience realized that our experiment was a ‘fiddle’, but equally surely, they accepted that the experiment could have been made more respectable given adequate time. But then it would have become a rather dull demonstration and it would have involved many more hours work in the preparation room. Actually this particular experiment could not be made too exact as one cannot correct for energy losses without assuming the end result. Another, probably less provocative, area where we felt justified in fiddling is illustrated by an experiment in electrostatics. We wished to charge a physically large capacitor consisting of two bent Nescafe tins placed some few inches apart. To produce an observable trace on the demonstration oscilloscope we shunted the tins with a 1F condenser. Had we used the most sensitive scope available, this ‘fiddle’ would have been unnecessary, but with its vast arrays of knobs it would be hard to convince anyone that such an instrument just measures potential differences. As no quantitative observations were made, no one was deceived; in fact, had we wished to take readings we would simply have scaled the values appropriately!
The third category of demonstration experiment was intended to teach genuine techniques and obtain equally genuine results; the ones using standard apparatus. When, for instance, we dealt with resonance we had a linear air track with a runner driven sinusoid-ally by the magnetic field of a solenoid. We tabulated amplitude against frequency, plotted an amplitude resonance curve, measured periodic and relaxation times, calculated Q and showed how it was related to the height and sharpness of the resonance. The precision of some of this was, part intentionally, not great, but we hoped to convey an image of scientists acting out their belief that the key to truth is in experiment (i.e., experience). Then sometimes we deliberately attempted experiments, often at the other one’s suggestion, that we knew would fail because of the magnitudes involved, the failure of an experiment can be informative in itself. Two examples of these failures are attempting to measure the force of gravitational attraction between a cabbage and a pair of shoes, and looking for deflection of a compass needle as a charged balloon is moved close by it. Even in standard working experiments it is often worth while not employing commercial demonstration apparatus. If it has a manufacturer's name attached it must work and give the expected answer or it would never have been marketed!
In using the blackboard we felt that only one of us, David, should write up the formal material. Knowing the undergraduate tendency to copy down what is on the board and to accept it as gospel even if riddled with errors, the board notes were thought out carefully in advance. Two different styles of layout, to say nothing of two styles of handwriting, could well be off putting. Of course while David was busy with the chalk Alan might be allowed to ask where this or that line came from, or why this integral was what was claimed for it, and he might be given the rude answer to check it for himself on a side board. In fact Alan had a doodle board for himself. Although the general banter over demonstrations was largely ad libbed we feel that board interruptions should be more carefully planned. Naturally there were occasions when the both of us did write up formal statements. An example of this was when were comparing our separate descriptions of systems in relative motion. Having two lecturers is ideal for discussing relativity!

Reflection
Student reactions appeared on the whole to be as favourable as students ever allow their reactions to be, and we briefly basked in the glory of being identified on buses in the remoter parts of Shoreham. The brightest students would probably have preferred a more rapid presentation of material, but we rather took the view that such individuals are able to look after themselves anyway, and consciously directed ourselves at the lower reaches. Certainly we feel encouraged to pursue matters further. Our colleagues have shown as much interest as academics allow themselves to display, mixed with some degree of suspicion and the feeling that it may be all very well for elementary courses but it would be inappropriate for advanced scientific material. They could be right but we should certainly like to tackle something more advanced if the opportunity should arise outside of the Palladium. We cherish the secret hope that even the Royal Society may not be deaf to our advances, and that the long lost disputation will be restored to favour.
Much may depend on the actual personalities involved but probably several interesting combinations may be found in any given group of lecturers. We have become convinced that, aside from purely technical matters of television and demonstrations, the dialogue idea merits wider attention. With two lecturers, differences of opinion can be articulated, alternative approaches may be presented, and the awful I found it on Mount Sinai approach avoided. Furthermore it becomes possible to draw an audience into the heart of a problem by encouraging them to take sides. Our own attempts at this have been only exploratory, but already when attending other first year lectures we find ourselves reformulating the material in dialogue form. Only forbidding growls from Whitehall will silence us now.

Reference
Blin-Stoyle, R J 1964, The Idea of a New University (London: Andre Deutsch), Daiches, D (Ed), p 120.