A student blogger who goes by Carolyn Blogs has an interesting entry on PowerPoint lectures from the perspective of someone taking the class:
Recently I came to the conclusion that I do not learn well from classes in which the lectures are based on PowerPoint presentations… Professors who use PowerPoint tend to present topics very quickly when they don’t have to do anything but talk. If every example and every diagram is on the screen, there isn’t much time for me to take notes on the subject of each slide. Lectures aided by chalkboard visuals are easier to take notes from because I can write what the professor writes on the board at the same time. Also, because there is usually more chalkboard space than screen space, if I am behind on note-taking, the visual will probably still be on the board for me to copy a few minutes later. A lot of professors try to solve this problem by handing out the lecture slides before class, or by posting them online. While this is great for a lot of students, it doesn’t work for me because I learn best and am most engaged if I have to take notes as if my grade depended on having a great record of the class and I would never see the material again. In classes with handouts, I tend to zone out and have to work harder to pay attention. Studies have shown[pdf] that taking high-quality notes improves organic memory: I rarely use my notes after the lecture because the act of physically writing information down helps me remember more of what goes on in class.
A few years ago I started phasing out PowerPoint from my upper-division classes (I never used it for grad classes). Carolyn hits on pretty much all the major reasons.
Teaching with PowerPoint has a different pace and structure than teaching with chalk or markers. It’s not just about overall fast vs. slow (though that’s part of it), but about when you go fast and when you go slow. When I use the board, I write down the major points, terms, definitions, etc. That forces me to slow down at exactly the moment when I’m making a big point and students should be attending closely. Once the critical information is on the board, I can elaborate, discuss with the class, ask questions, etc. while it hangs up there behind me for students to refer to. And since writing slows me down, I don’t give as much emphasis to relatively minor points — giving students an additional cue as to what’s more and less important. (“Don’t ignore this completely, but it’s not as central as what I said earlier.”) You can reproduce this kind of pacing and structure with PowerPoint, but in practice it’s difficult to do during a live performance in front of a classroom. You have to write your presentation with delivery (not just content) in mind. Otherwise it’s just too easy to blow through major and minor points at a constant pace.
Another point that she makes… I still use PowerPoint in my big introductory classes (though I make my own slides from scratch, use animation to help regulate my delivery, and try to avoid the mind-numbing bullety templates). I always have a few students ask me to post the notes before class. I don’t — I post them after class, but honestly, I have sometimes wondered if I’d be better off not posting them at all. Carolyn modestly writes “while [posting notes] is great for a lot of students, it doesn’t work for me…” but I actually think this describes most students. A lot of students misread their internal cues — if it feels like they are expending a lot of effort then they think they must be struggling with the material. Actually, though, if the professor is presenting challenging material, then you shouldn’t feel relaxed — relaxation is a sign that you’re probably thinking superficially or zoning out, not that you’ve quickly mastered the material.
I also found it impressive that Carolyn reached this conclusion on her own. Because frankly, it’s fundamentally very difficult to introspect into your own learning processes. A few years back, when I started moving away from PowerPoint, I got feedback on my student evaluations from people who wanted more PowerPoint. When I talked with students who felt that way, they thought they’d be able to focus more on the material if they didn’t have to bother taking notes. I realized that reflects a fundamental misunderstanding of what note-taking does for you. I’ve been getting less of that feedback lately — maybe because I’ve gotten better at using the board, or maybe because recent students have been around PowerPoint longer and see its limitations more clearly.