Despite the concerns regarding value-added models (VAMs), advocates hold strong to VAMs' theoretical strengths and potentials, while adopting a set of agreed-upon albeit "heroic" set of assumptions, without research in support. These assumptions transcend promotional, policy, media, and research-based pieces, but they have never been…

The single best predictor of who will be a great teacher next year is who was a great teacher this year. Some great teachers are seasoned veterans, while some are new to the field. Experience matters, of course, particularly in the early years of a teaching career, but it's no guarantee of teacher effectiveness. There is a wide variation in…

The educational reform movement in the United States has resulted in a variety of states moving toward a system of value-added modeling (VAM) to measure a teacher's contribution to student achievement. Recently, many states have begun using VAM scores as part of a larger system to evaluate teacher performance. In the past decade, only "core…

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…