External validity: four models of improving student achievement

Randomized controlled trials in lower-income countries have demonstrated ways to increase learning, in specific settings. This study uses a large-scale, nationwide RCT in Ghana to show the external validity of four school-based interventions inspired by other RCTs. Even though the government implemented the programs within existing systems, student learning increased across all four models, more so for female than male students, and many gains persisted one year after the program ended. Three of the four interventions had a similar cost effectiveness. The intervention that directly targeted classroom teachers increased the likelihood that teachers were engaged with students.