An experiment on the motivation of teachers

I am not aware of teaching experiments, esp. combined with experiments on altruism. It would be nice to investigate how much effort people would put into teaching if they were simply asked to teach another party the game form, got a fixed payoff for this, or various shares of their "student's" earnings.

As always, the external validity of such an experiment would be limited, but I am fascinated by some thoughts on how some public servants' motivation dwindles when they get better paid and perhaps obvious that they are actually paid for their efforts, however heroic. Check out Uri Gneezy's experiment and an Economist review of a book I enjoyed.