“What matters most in a child’s development, they say, is not how much information we can stuff into her brain in the first few years. What matters, instead, is whether we are able to help her develop a very different set of qualities, a list that includes persistence, self-control, curiosity, conscientiousness, grit, and self-confidence. Economists refer to these as noncognitive skills, psychologists call them personality traits, and the rest of us sometimes think of them as character.”