We use a novel database of the preservice apprenticeships ("student teaching placements") of teachers in Washington State to investigate the relationship between mentor effectiveness (as measured by value added) and the future effectiveness of their mentees. We find a strong, positive relationship between the effectiveness of a teacher's…

State-specific licensing policies and pension plans create mobility costs for educators who cross state lines. We empirically test whether these costs affect production in schools--a hypothesis that follows directly from economic theory on labor frictions--using geo-coded data from the lower-48 states. We find that achievement is lower in…