This is a personal preference, because slides present a barrier between the instructor and the student. It is far too easy to lecture to the slides, and let the slides dictate the lecture. They do it occasionally at first, and then as the subject matter gets more complex, their hands remain riveted to the bullets as they speak. Soon, they begin talking at the slide. As far as that instructor is concerned, the students are gone until the slide show is over.
Slides distract attention away from the instructor and away from what is written on the board.
The instructor should be able to communicate important and difficult concepts using words and body language. Slides distract the instructor s attention from the students. If the instructor is spending time clicking to move the slide show along, he isn t paying attention to the audience's level of awareness and connection to the material. When drawing diagram, the more colors the better. People pay more attention to the nuances when they are highlighted in different colors.