My daughter thinks math is hard. She also thinks she is not good at it. She is, by some set of objective measures, actually quite good at it. But she keeps repeating this mantra to me when we are sitting there slogging through her homework. I tried all kind of positive reinforcement and then, one day, I sat her down, and explained that there is a widely held gender bias belief about girls doing worse in math. It didn’t really make a difference.