Thanks to Daryl at Anecdote for spotting this: The fine art of (not) lecturing

Don't drone. Get students talking and guessing and arguing. Our short-term memory can only process four ideas at a time, he warns, so don't try to cram whole chapters into an hour. In a nutshell: reduce the load; stimulate the brain.

"I can't imagine a three-hour lecture, personally, but getting students to flex their brains during class rather than just sit there passively is exactly what we want to see," Wieman said in an interview.

It's that interaction – the answering and arguing and persuading – that stimulates protein in the brain, which in turn helps anchor ideas into long-term memory, he says.