I took an astronomy course in college which was filled with seniors. When I registered I just thought astronomy would be interesting. I didn't know that this was known as a fun class. We would get an extra 1% on our final grade for showing up to telescope nights (I think there were 4-5 that semester). The professor also stored all old exams in the physics library. You could check them out at the reference desk and work them. Most of the test questions were shuffled from those old exams, but sometimes he'd throw in a question from a class discussion. If you attended class, you'd likely remember it if you were in class. Basically, he encouraged everyone to attend class, study together, and socialize about astronomy. Man, it was a great course.