In my first year teaching I gave my students so much candy as reward for behaving that my class had a cavity epidemic. I was afraid that if I didn't bribe my students with candy they wouldn't participate. And I wasn't alone. Lots of teachers hand out small rewards, from candy to stickers, as a way of encouraging good work.

But according to research from Allen Gottfried, a professor of psychology at Cal State Fullerton, receiving all those external rewards might actually stunt the development of a student's leadership abilities.