Association for Public Policy Analysis & Management

It is well-established that there is wide variation in teacher quality. However, there is a paucity of rigorous empirical evidence on interventions that improve teacher effectiveness. We analyze a field experiment in which middle-school math teachers were randomly granted access to “off-the-shelf” lessons designed to facilitate deep understanding. Some teachers also received access to online resources to facilitate lesson adoption. To inform our empirical work, we model teaching as involving two complementary tasks; introducing concepts and developing understanding. Absent any outside assistance, teachers must be effective at both tasks to be effective overall. However, “off-the-shelf” lessons designed to develop understanding can substitute for teacher skill on this same task so that teachers with access to these lessons only have to be good at introducing concepts to be effective overall. We find that providing access to the lessons and promoting their use increased students’ average math achievement by 0.085 standard deviations. These effects are much larger for weaker classrooms (teachers), suggesting that “off the shelf” lessons were able to compensate for deficiencies in teacher skill. We also employ extensive teacher and student survey data to provide evidence on underlying causal mechanisms. A cost-benefit analysis reveals that this intervention was much more cost effective than many well-known successful programs.