Opaque Transparencies
Due to Rolf G. Winter; published in Physics Today, April 1991, page 134. Winter was pleased to acknowledge the help of many colleagues who, by their example, contributed to these guidelines.
 
  • Write to within 1 mm of the edge so that is is easy to let either the screen of the projector cut off some material. The audience will pay more attention if it is forced to guess.
  • Use pale, transparent colors. Pale green is particularly good; it can seldom be read from beyond the second row.
  • Color that is used consistently makes things too easy to follow and causes somnolence. Change color erratically within each equation. The audience may be inspired to credit with lines of reasoning that never occurred to you.
  • Data points in graphs must be indistinguishable from flyspecks. You can then decide on the spot, so to speak, whether to claim agreement or disagreement with theory. Such decisions should be made after one senses the mood of the audience.
  • Before the talk, project your transparencies in a room similar to the one that will be used. If anything can be deciphered with the aid of opera glasses from the middle of the room, write smaller.
  • Plan the time for each transparency. A useful formula is
    			            4 PI
    	t(seconds) = -------------------------------------
                         exp( number of eqs. on transparency )
    
  • If your are offered the insult of being scheduled in a small room, have the projector placed low so that it must be angled upward toward the screen. The importance of your talk is then made manifest by the keystone-shaped illuminated region, and some of the area will necessarily be out of focus.
  • Obscure. You may try to stand so as to block the view of the screen, but there will usuually be some who can see. It is more effective to stand very close to the projector and intercept about a third of the light with your shoulder. Point to things directly on the transparency with as blun an instrument as is available. Your finger can be effective, but a blackboard eraser is superior.
  • Make it clear that your are a perpetually jet-setting speaker who doesn't think the present audience is worth much preparation. Your transparencies should be smudged and scratched, and some should be out of order. Emphasize that they have been written at 30.000 feet. ''Let's see what's on the next one'' is always a useful insult. Mumble something about having used this stuff for the principal talk at the Belgrade summary of the Tokyo Conference, and about having been too busy to sort it out since.
  • Bring a very large stack of transparencies, on any subject, that you do not show during the talk itself. If anyone asks a question at the end, furhter impertinence can be headed off by showing 17 of them.