"[R]ising income inequality explains, at best, half of the increase in the rich-poor academic achievement gap. It’s not just that the rich have more money than they used to, it’s that they are using it differently. This is where things get really interesting. High-income families are increasingly focusing their resources — their money, time and knowledge of what it takes to be successful in school — on their children’s cognitive development and educational success. They are doing this because educational success is much more important than it used to be, even for the rich."