Both of my twins have been awarded these buttons at school for solving particularly gnarly math problems. If they wear these buttons on test days, and get 100% on the math test, they get extra credit. Interesting approach. Is it really the best students who need extra credit? I think if I were a teacher, I would devise a way to reward credit to students who struggle valiantly.
Nevertheless, I'm incredibly proud of my kids for earning these. I'd be interested in hearing your take on it.