We study whether reallocating existing teachers across schools within a district can increase student achievement, and what policies would help achieve these gains. Using a model of multi-dimensional value-added, we find meaningful achievement gains from reallocating teachers within a district....

To the extent that students benefit from high-achieving peers, tracking will help strong students and hurt weak ones. However, all students may benefit if tracking allows teachers to present material at a more appropriate level. Lower-achieving pupils are particularly likely to benefit from...

Teacher value-added (VA) measures how teachers improve their students' contemporaneous test scores. Many teachers, however, argue that contemporaneous test scores are a poor proxy for their permanent influence on students. This paper considers a new VA measure -- 'long-run VA' -- that captures...

This paper documents a new empirical regularity: teacher value-added increases within-teacher when accountability incentives are strengthened. That finding motivates a strategy to separate value-added into incentive-varying teacher effort and incentive-invariant teacher ability, combining rich...