Increasing the efficiency of the school system is a primary focus of policymakers. I analyze how the time of day affects students’ productivity and if efficiency gains can be obtained by rearranging the order of tasks they perform throughout the school day. Using a panel data set of nearly 2 million sixth- through eleventh-grade students in Los Angeles County, I perform within-teacher, class type, and student estimation of the time-of-day effect on students’ learning as measured by GPA and state test scores. I find that given a school start time, students learn more in the morning than later in the school day. Having a morning instead of afternoon math or English class increases a student’s GPA by 0.072 (0.006) and 0.032 (0.006), respectively. A morning math class increases state test scores by an amount equivalent to increasing teacher quality by one-fourth standard deviation or half of the gender gap. Rearranging school schedules can lead to increased academic performance.

Test score measures of teacher quality may not fully capture teachers’ impact on students. We use test score and non–test score measures of student achievement and behavior to estimate multiple dimensions of teacher quality. We find that these two measures of teacher quality are only weakly correlated and that both affect students’ high school performance. A teacher removal simulation that uses both measures improves most long-term student outcomes by over 50%, compared to a policy that uses test scores alone. Our results also show that for high school outcomes the effects of teachers in later grades are larger than those in earlier grades and that performance in core elementary school subjects matters more than that in other subjects.