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.