I'm in a seminar on nonphotorealistic rendering. Right now it's fairly hardcore: the slides are about differential geometry and how to derive the principal curvatures for a surface at a point.
Three rows up and five seats to the left is a former UNC student who's now a professor at UMBC. No doubt she already knows this stuff -- Penny has her own research agenda in NPR and illustration -- so she's working on something to keep her brain occupied.
Like so many extraordinarily smart people I know, she's knitting. Why is it that all of a sudden it seems like half the people I know are doing this?
A good friend of mine used to tat when we were both studying in Spain. If your hands are busy doing something that doesn't require a lot of thought you brain is free to concentrate on other things like the lecture you're at. :-)