Teacher professional development absorbs billions of dollars each year and lots of teacher time, yet there’s hardly any evidence that teacher training actually improves teaching. A massive 2014 meta-analysis by the federal Institute of Education Sciences, for instance, evaluated 643 studies of PD in K-12 math instruction and found just two that met the evidentiary bar set by the What Works Clearinghouse and had positive results. Linda Darling-Hammond, a former president of the American Education Research Association, has frankly noted that the “training [educators] receive is episodic, myopic, and often meaningless.” Well, Brown University’s John Papay and Nathaniel Schwartz and Harvard’s Heather Hill—all scholars at the Annenberg Institute—think folks like me are unduly pessimistic on this score. They’ve dug into PD to see what’s working and what we can do better (see their brief here). I thought it worth sharing their take.