The 'detective story' principle and puzzle-solution formats

The last two posts have featured comments on using slides and visual aids by the late Sir Lawrence Bragg.

But he also had a good understanding of the effectiveness of story-telling and leading audiences to the solution of a puzzle in presentations:

'There is a most important principle which I think of as the 'detective story' principle. It is a matter of order. How dull a detective story would be if the writer told you who did it in the first chapter and then gave you the clues.

'Yet how many lectures do exactly this. One wishes to give the audience the aesthetic pleasure of seeing how puzzling phenomena become crystal clear when one has the clue and thinks about them in the right way. So make sure the audience is first puzzled.

'A friend of mine, a barrister, told me, that, when presenting a case to a judge, if he could appear to be fumbling toward a solution and could entice the judge to say "But, Mr. X, isn't the point you are trying to make this or that?" he had as good as won the case.

'One wants to get the audience into this frame of mind, when they are coaxed to guess for themselves what the answer is. Again I fear I am saying the trite and obvious, but I can assure you I have often sat and groaned at hearing a lecturer murder the most exciting story just by putting things in the wrong order.'

(From Advice to Lecturers: An anthology taken from the writings of Michael Faraday & Lawrence Bragg, London: The Royal Institution of Great Britain, 1974, ISBN 07201 04467).

Although Bragg was dealing here with the overall structure of a lecture or presentation, much shorter puzzle-solution formats are also one of the main rhetorical techniques discussed and recommended in my books, and I posted some video clips of them triggering applause HERE.

Showing what you mean: more from Professor Sir Lawrence Bragg

The previous post featured a comparison between the use of slides and drawing on a board by the late Professor Sir Lawrence Bragg, who continued the Royal Society's Christmas lectures for children that Michael Faraday (left) had started in the nineteenth century. Here's a related gem from Bragg'*:

'To the layman the difference between the description of an experiment and the actual witnessing of it is as great as the difference between looking at a foreign country on the map and visiting it; we grasp its geography in a far more vivid way when we have been to the place.

'One is struck again and again by the immense superiority, as judged by the effect on the audience, of a series of experiments and demonstrations explained by a talk over a lecture illustrated by slides. The Christmas Lectures to young people at the Royal Institution afford a good instance.

'It is surprising how often people in all walks of life own that their interest in science was first aroused by attending one of these courses when they were young, and in recalling their impressions they almost invariably say not 'we were told' but ‘we were shown’ this or that’ (Bragg’s own emphasis).

(*Advice to Lecturers: An anthology taken from the writings of Michael Faraday & Lawrence Bragg, London: The Royal Institution of Great Britain, 1974, ISBN 07201 04467).

A Nobel prize winner’s view on slides versus ‘chalk and talk’

One of the best things I’ve ever read on presenting complicated technical material to audiences is an anthology published by the Royal Institution that was taken from the writings of Michael Faraday (19th century pioneer of magnetism and electricity) and Lawrence Bragg (20th century Nobel prize winner).

Both of them were famous for their ability to take audiences, whether lay or professional, to the frontiers of science.

Writing decades before the invention of PowerPoint, Bragg had this to say about slides and ‘chalk and talk’ (which isn't a million miles away from some of the points in my last three posts on the subject):


'Lecturers love slides, and in a game of associations the word 'lecture' would almost always evoke the reply 'slide'. But I think we ought to apply to slides the same test, 'What will the audience remember?'

'Some information can only be conveyed as slides, photographs, or records of actual events, such as the movement of a recording instrument, for instance, a seismograph. But slides of graphs or tables of figures are in general out of place in a lecture, or, at any rate, should be used most sparingly, just because the audience has not time to absorb them.

'If the lecturer wishes to illustrate a point with a graph, it is much better to draw it, or perhaps clamp the component parts on a magnetic board or employ some device of that kind.

'I remember well the first time I was impressed by this latter device, during a lecture on airflow through turbine blades. The lecturer altered the angle of incidence and the air arrows by shifting the parts on the board.

'It is again a question of tempo – the audience can follow at about the rate one can draw (my emphasis); one is forced to be simple, and the slight expertise of the drawing holds attention. One must constantly think of what will be retained in the audience’s memory, not of what can be crammed into the lecture.'

(From Advice to Lecturers: An anthology taken from the writings of Michael Faraday & Lawrence Bragg, London: The Royal Institution of Great Britain, 1974, ISBN 07201 04467),