There was a grand mystery surrounding education: Why were some students learning a lot, and other students not so much? Politics, race, economics, and culture have all been invoked as explanations. But the data is in, and it shows that the divide between the learned and the not-so-learned does not fall neatly along any of the typical sociological divides.

One might suspect that money and social privilege explain the discrepancy, but here, too, the data does not back the thesis. Consider the results of PISA (Program for International Student Assessment), an exam that grade school students from most of the world’s countries now take. Even though the United States is a well-off nation and is second in the world in per capita educational spending, its students’ scores are consistently average by international standards. American students from well-to-do families and access to the best preparatory schools do not score significantly better than similarly privileged students from other countries. In fact, they did worse than twenty-seven different countries in math. In 2009, the United States ranked twenty-sixth in math, seventeenth in science, and twelfth in reading.

Long story short—the world has changed. The United States is no longer the golden standard for education, and money is clearly not the main determinant of success.