Growing evidence suggests that contrary to popular belief, schools mostly do not generate achievement gaps in cognitive skills but, rather, reflect the inequalities that already exist. In the case of socioeconomic status, exposure to school often reduces gaps. Surprisingly little is known, however, about whether this pattern extends to gender gaps…

When do children become unequal in reading and math skills? Some research claims that inequality grows mainly before school begins. Some research claims that schools cause inequality to grow. And some research--including the 2004 study ''Are Schools the Great Equalizer?''--claims that inequality grows mainly during summer vacations. Unfortunately,…