You don't need slides to support your notes. There are two kind of classes: those that bring you up to speed; all the stuff there is found in textbooks or revi

You don't need slides to support your notes. There are two kind of classes: those that bring you up to speed; all the stuff there is found in textbooks or review papers. And those that present wholly new ideas (research seminars, conferences,) where you can just read the paper or the preprint for details. The only time I've seen something on the board that I really had to copy down to keep an copy of was exercises and their solutions.