Estimating Classroom-Level Influences on Literacy and Numeracy: A Twin Study "[G]enetic factors accounted for between half and three quarters of the variance across most domains and grades... Classroom effects were mostly nonsignificant." Bummer.
Twin study suggests that the impact of classrooms and teachers on literacy and numeracy in early years is very small. Good thing we haven't had decades of multiple administrations suggesting that teacher quality alone could boost these things....
New twins study claims negligible effect of classroom on achievement, no measure of classroom differences, kind of hard to interpret ($)
Research: maybe teachers don't matter?