Efforts to improve education outcomes often involve lengthening the school day or the school year in hopes that spending more time in school will boost student learning. Yet, as Frederick Hess explains, U.S. students spend as much or more total time in school as their peers in other industrialized nations. What matters more than the amount of time is how that time is used. Although research into time usage at school is limited, existing studies have shown that much time spent in school time does not involve actual learning time, either because of interruptions or other non-learning activities or because students are not engaged. Hess suggests that, before adding time to the school day or year, it's important to understand what schools are doing with their time, rethink their routines, and seek to ensure that they are using time wisely and well.