Purpose: A growing trend in instructional improvement efforts is the use of formative assessment informed by research-based developmental trajectories of how students gain deeper understanding of subject matter content over time. This article reports the findings of a large-scale experimental study of an innovative mathematics professional…

Historically, reforms designed to transform teaching from rote, teacher-centered instruction to progressive student-centered instruction have had varied levels of success. Plentiful research juxtaposes teachers' enacted instruction with the instructional ideals of reform efforts to determine the extent to which teachers' instruction aligns with…