Students in the United States spend much less time in school than do students in most other industrialized nations, and the school year has been essentially unchanged for more than a century. This is not to say that there is no interest in extending the school year. While there has been little solid evidence that doing so will improve learning…

Tracking students into different classrooms according to their prior academic performance is controversial among both scholars and policymakers. If teachers find it easier to teach a homogeneous group of students, tracking could enhance school effectiveness and raise test scores of both low- and high-ability students. If students benefit from…