The power of feedback to students learning mathematics was highlighted by Baker, Gersten, and Lee (2002). They found that the highest effects accrued when teachers provided feedback data or recommendations to students (d = 0.71), then for peer-assisted learning (d = 0.62), explicit teacher-led instruction (d = 0.65), direct instruction (d = 0.65), and concrete feedback to parents (d = 0.43).

