Esther Duflo, a French economics professor at MIT, wondered whether there was anything that could be done about absentee teachers in rural India, which is a large problem for remote schoolhouses with a single teacher. Duflo and her colleague Rema Hanna took a sample of 120 schools in Rajasthan, chose 60 at random, and sent cameras to teachers in the chosen schools. The cameras had tamper-proof date and time stamps, and the teachers were asked to get a pupil to photograph the teacher with the class at the beginning and the end of each school day.
It was a simple idea, and it worked. Teacher absenteeism plummeted, as measured by random audits, and the class test scores improved markedly.