dave-in-nj:
looking back, I think we let you down.
I'm not at all sure about that. There were 4 pages of stuff in the other Thread - a lot of people made an effort.
The two sides of the coin are teaching and learning. The student (assuming he wants to learn and is not just attending class because he can't find any more windows to break) has an obligation as much as the teacher has.
In my experience the most useful thing a student can say is "I don't understand" rather than (as is more common - especially in adults) pretending to understand for fear of looking stupid. (And if you want some fun it can also be a great way of exposing the teacher's pitiful knowledge)
...R