Nothing matters more to student learning than teacher quality. Not class size, not poverty, not family background, not even overall school quality.
This was the key takeaway from a highly controversial Los Angeles Times analysis of teacher value-added scores for students in the L.A. Unified School District. The significance of this finding can't be understated. Many people still believe either that "these kids can't learn" or that "school can only do so much with kids like this until society fixes their families and communities."