1.1. What does this study tell us about one of the possible sources for wage inequality in the United States? We describe in the text the role played by education on an individual’s earnings. But recent work tells us that what matters is not just how much education you get, but what that education was like. In particular, it seems to matter a good deal how good your teachers were.

A group of economists, including Raj Chetty and John Friedman, took a look at the careers of 11,000 students who had taken part in an education program launched in Tennessee in the late 1980s. Importantly for the economists, students were randomly assigned to either a small or large class.

Teacher assignments were also random across these classes.

Chetty and his colleagues were then able to match these students with tax data from many years later.