I used to use powerpoint for my classes. A few years ago, something messed up, and I could only use the blackboard. Guess what? Best. Class. Ever. Now, my scheme is to teach the way people taught 100 years ago. I talk to my students. I write important things on the board (at, it should be said, the exact same speed as they can take notes). I have a stack of slides with illustrations of things that are too complicated to draw on the board, and I select from this stack occasionally. (Those slides are also on the course website, so students can print them if they want to insert them in their notes.) All of this works very well. At first, the students are freaked out by the fact that they have to attend class, and pay attention, and take notes. But, in the end, quite a lot of the class reviews point out that the blackboard is much better than powerpoint.