Do Friends Improve Female Education? The Case of Bangladesh

We randomly assign more than 6,000 students to work on math tests in one of three settings: individually, in groups with random mates, or in groups with friends. The groups consist of four people and are balanced by average cognitive ability and ability distribution. While the achievement of male students is not affected by the group assignment, low-ability females assigned to groups outperform low-ability females working individually. The treatment is particularly effective when low-ability females study with friends. To rule out sorting effects, we show that random groups with identical composition to that of friendship groups do not produce similar effects. Our study thus documents that there are teaching practices where mixing students by ability may improve learning, especially for low-ability female students.