Good teachers are the backbone of a successful education system. Yet, in developing countries, teachers' content knowledge is often inadequate. This study documents that primary school math teachers in the department of Moraz'an in El Salvador only master 47 percent of the curriculum they teach....

Good teachers are the backbone of a successful education system. Yet, in developing countries, teachers' content knowledge is often inadequate. This study documents that primary school math teachers in the department of Moraz'an in El Salvador only master 47 percent of the curriculum they teach....