[vidarh]

My two best teachers (this was in Norway) took two very different approaches. One basically gave me a free reign to move ahead of the rest of the class and brought in more advanced text books for me, let me suggest my own homework etc. It took extra work for her, so I was lucky she put in the effort.

The other did what you suggest, and would have me go around and help others as soon as finished my own work. It was useful as a means to learn to understand what other people found difficult and why. It might not have helped that much with my understanding of the subject (maths) itself, but it helped with problem solving skills - having to come up with different ways of explaining things or approach a problem from different angles to whichever one I thought was most obvious when that "obvious" angle didn't work for someone else, and I think that was useful.