Illegible and incomprehensible visual aids often result from confusion about sizes of lettering and symbols between the original artwork and its projected image. This paper discusses legibility standards used by industry and basic mathematical exercises to assure legibility of copy on visual aids used as original art or as reproduced slides.

Careless handling of the overhead projector drains the communications value of presentations. The four most serious problems are: the keystone image; cluttered visuals; speaker blocking the image; and careless handling of the projectuals. These problems are discussed and simple solutions are offered in each case.