Taking a class that is interesting but extremely hard and obscure... is that a good idea? I took an "intro" to physics class where my teacher was a Russian genius and taught us about special relativity and space-time diagrams and all sorts of interesting material. But when it came to tests, the information was just too hard to regurgitate onto paper.

Is it worth taking a class for fun at the risk of lowering GPA?

I think so, but it turns out that my class had a very nice curve.