This report synthesizes some intriguing research on professional development. Here's the passage that blows my mind:
"Intensive professional development efforts that offered an average of 49 hours in a year boosted student achievement by approximately 21 percentile points. Other efforts that involved a limited amount of professional development (ranging from 5 to 14 hours in total) showed no statistically significant effect on student learning" (p. 9).
The authors concede that the data set is limited (meta-analysis found only nine well-designed studies). But this should give pause to anyone who plans one-time-only PD experiences. How much can we really learn in an hour or two, if it's not connected to other experiences and has no follow-up?
It gives me further confidence that PD needs to be ongoing and focused on practice.
Check out the report for other insights: Darling-Hammond, L., Wei, R. C., Andree, A., Richardson, N., & Orphanos, S. (2009). Professional learning in the learning profession. Washington, DC: National Staff Development Council.