This paper reports on a field experiment in 82 high schools trialing a low-cost intervention in schools’ operations: teachers working in the same school observed and scored each other’s teaching. Students in treatment schools scored 0.07 student standard deviations higher on math and English exams. Teachers were further randomly assigned to roles—observer and observee—and students of both types benefited, observers’ students perhaps more so. Doubling the number of observations produced no difference in student outcomes. Treatment effects were larger for otherwise low-performing teachers.

Online college courses are a rapidly expanding feature of higher education, yet little research identifies their effects relative to traditional in-person classes. Using an instrumental variables approach, we find that taking a course online, instead of in-person, reduces student success and progress in college. Grades are lower both for the course taken online and in future courses. Students are less likely to remain enrolled at the university. These estimates are local average treatment effects for students with access to both online and in-person options; for other students, online classes may be the only option for accessing college-level courses.