Powerpoint may hinder learning
Powerpoint is the Big Thing at the moment - talks are all done with Powerpoint slides accompanying, even lectures and school classes are now often done with Powerpoint. But new research from UNSW suggests that having the same text on your Powerpoint slides as what you’re saying may actually limit the audience in what they can learn. Apparently our “working memory” is really only good at handling two or three tasks at the same time - if it tries to listen and read at the same time, it’s got limited space left for actual thinking and processing.
They suggest that diagrams and pictures on slides are fine (since these present the information in a different way) but using text detracts from the rest of your talk.
I’ll have to think about this a bit more - I do like having some text on the slides so that if I tune out for a few seconds (minutes…) I don’t completely lose the plot. But I definitely don’t write all my text on there (and read verbatim - very, very bad). On the other hand, when I first started giving talks, I preferred to use no slides - I liked people not to be distracted from what I was saying by reading ahead (or behind). If this research really does hold water, I’ll have to think more about my own presentation style.
Another point they make is that students learn more (in a talk, anyway) from being presented with worked solutions - so their brain can devote itself to understanding and remembering, rather than solving. I’d certainly like to see more of their research first though 
I agree that I like some text as I tune out as well. As for presenting worked solutions, I can see the logic there. Sometimes it is good to just see how methods are implemented. My brain is not always up for creative problem-solving during a lecture. I tend to work backwards and extract general rules from examples. For example, I didn’t fully appreciate the difference between differentiability and continuity until I came across the Weierstrass function ( http://en.wikipedia.org/wiki/Weierstrass_function ), even though I had been taught the definitions for those two things.