My favorite math class (undergrad) was a new course one professor wanted to offer for seniors. He called it Math Seminar, and each week we were handed a set of

My favorite math class (undergrad) was a new course one professor wanted to offer for seniors. He called it Math Seminar, and each week we were handed a set of problems chosen from abstract algebra, real analysis, topology, or number theory. Each student chose a problem and a day to present their solution next week. All class time was spent on presentations and questions to the presenters. IIRC, not finding the solution wasn't a big enough penalty to fail, as long as the professor thought you researched it and tried multiple approaches. I have fond memories of nights at a local bar, working through a problem.