Document Number: 11062Summary of Research on the Effectiveness of Math Professional Development Approaches - Of 643 studies conducted in the United States related to professional development interventions for teachers of K-12 math, five met What Works Clearinghouse standards with or without reservations. Of those five, two found positive effects on students' math proficiency. This means there is limited evidence to guide districts and schools in selecting an approach, or to support developers' claims. Districts and schools must use best judgment until more causal evidence becomes available. (Russell Gerston, et al., National Center for Education Evaluation and Regional Assistance, REL Southeast, January 2014)...