Real analysis was the hardest class I ever took, and I didn't even really have to. Barely scraped a C, but I wear it more proudly than most of the A's I've ever gotten.
We use the Moore Method at UT. We started with a series of axioms and over the duration of the semester we built and proved ourselves as a group every theory. And only those theories successfully proven by the group were admissible on tests. It was rad as hell.
Different contexts, but that reminds me of a sort of "second class, taken after introductory programming" survey class of the CS domain, taught by another rather intense professor. I learned more in those 12 or so weeks than in most other classes. It was intense, but left one with a rather good, basic survey -- which is no mean feat, given the breadth of the domain (from boolean logic and gates up through higher level languages, discreet mathematics, statistics and O notation, etc.)
People who thought they were getting a typical "survey" class -- LOL! This professor wasn't having any of it.
Perhaps a bit unfair, if you were trying to balance an overall course load that was already heavy. But of itself, worth it.
