When I worked for The Princeton Review, one of the things we used to tell students was that the only thing that really significantly correlated with test scores was income. If you had more money, you'd generally do better, no matter how you had done in school, how much you studied, whatever. It definitely motivated kids to prepare for test, but it also made me really sad. Now that standardized tests are becoming mandatory, people in Florida have noticed that better libraries mean better scores, even as the amount spent on most of those libraries is "pitiful". [thanks mac]