A transparency and a lecture using transparencies. (No relation to the advice.)
Bad - When you give a talk with transparencies or computer presentations, don’t go over the content of the transparencies but rather assume that the audience reads and digests them while you develop the matter even further and make comments about their content.
Worse - The same as above, except that the transparencies are very dense and technical and hard to understand.
Worst – The same as above except that the transparencies are handwritten in an unreadable way.
Answer to Trivia question:
Q: What do Yehuda Agnon, Michael Ben-Or, Ehud Lehrer, Uzi Segal (whose calibration theorem was mentioned in the post on the controversy around expected utility theory), Mike Werman, myself, and quite a few others, all have in common?
Answer: We all, (and altogether more than 20 students) took part in Benjy Weiss’s mathematics course for high-school students in 1970/1. The picture is of Weiss and his Ph. D. supervisor William Feller in Princeton. From Jay Goldman’s photo album. About twenty years later I gave a similar course to six high-school students, 3 Assafs, 1 Matan, 1 Tomer and 1 Elon.