When I lecture in a math class, I use a whiteboard and expect the students to take notes. Because it is unlikely they will write down most of what I say, their notes will not be nearly as good a resource as the textbook. I expect them to write what I write, and I don’t really care if they look at it again. Writing it down will help them remember.
That isn’t to say that their notes are useless. I don’t cover everything in the textbook and the class notes tell them what I will test on. I also cover some things that are not in the textbook, especially tips on using the graphing calculator. I also deliberately give different examples than the textbook, which gives them a variety of examples covering the same material.
I devote about half of the class time to having students work problems. Sometimes they refer to class notes while doing so and sometimes they look in their textbooks. Some of them don’t need either, because everything is fresh in their minds.
Some teachers use powerpoint and give the students copies. I don’t like this because it deprives the students of the learning tool of writing the material. I recently read an article saying that whiteboards are an old fashioned way to teach, and should not be used. I think that blackboards are old fashioned because the chalk is annoying. I am in favor of whiteboards.