I think in a formal classroom setting, I found that you wouldn't know if they can comprehend the material or not because they don't ask questions at the end. They don't unless you call on them. They're not going to volunteer and ask questions. It's not going to be a discussion. A lecture is a lecture. And the instructor is "right." And so they're not going to challenge that. There was, in fact, a lesson that I taught one time where I was wrong. And the slides were...it was my fault. But anyway, no one corrected me until one of the instructors afterward came and said, you know, we've looked at the slides and perhaps you might need to change something. And no one had said anything in the course. I'm sure they all noticed. All the students I'm sure had noticed, but none of them said anything.