Whether you average that across five school days or a seven-day week, that's not much work - especially when you consider that American children spend fewer hours in the classroom than their counterparts in many other nations. Only one student in five reported spending more than 10 hours a week on homework. American students routinely tell researchers their schools don't demand that they work as hard as they can. But that seems to be good enough, as two-thirds of the students surveyed reported that their grades are A's and B's.

Because in South Korea, almost every young person graduates from high school. From the earliest years, the drive to get into good universities shapes a focus on achievement that keeps students in schools for long hours, sharpens the curriculum and makes education the focal point of families. It surely takes a toll, but it would be hard to argue that this commitment hasn't boosted South Korea's phenomenal economic trajectory.