Improving teacher evaluation is one of the most pressing but also contested areas of educational policy. Value-added measures have received much of the attention in new evaluation systems, but they can only be used to evaluate a fraction of teachers. Classroom observations are almost universally used to assess teachers, yet their statistical…

Unlike in elementary school, high-school teacher effects may be confounded with both selection to tracks and unobserved track-level treatments. I document sizable confounding track effects, and show that traditional tests for the existence of teacher effects are likely biased. After accounting for these biases, high-school algebra and English…

Effective teachers have an enormous impact on the lives of their students. Great teachers can help students who are behind academically catch up to grade-level expectations. By accelerating student performance, they can help close the opportunity and achievement gaps that cut short the college and career dreams of so many low-income students and…