American schools need more time if they are to teach efficiently. The school year is fixed at or below 180 days in all but a handful of states – down from more than 190 in the late nineteenth century, when Saturday-morning sessions were common. The instructional day is only about six hours, of which much is taken up with nonacademic matters. In 1994, a national commission calculated that in four years of high school a typical American student puts in less than half as much time on academic subjects as do students in Japan, France and Germany. Extending the school day or the school year can get expensive and complicated, and reducing nonacademic electives and physical education brings complaints from parents and students alike. But there is one quite cheap and uncomplicated way to increase study time: add more homework. You may not be surprised to learn that homework raises student achievement, at least in the higher grades. For young children homework appears not to be particularly helpful. Even among older students it is hard to be sure of the extent to which more homework may lead to higher achievement.