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RWJF Program Evaluations

An RWJF Collection

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Effects on Play, Physical Activity and Recess

Impact and Implementation Findings from an Experimental Evaluation of Playworks

 Students running in a race over a school field.

Mathematica Policy Research and the John W. Gardner Center for Youth and Their Communities at Stanford University conducted a randomized controlled trial of Playworks, a nonprofit organization that delivers a safe, healthy recess in low-income elementary schools in 22 U.S. cities. They collected data from students, teachers and school staff at the schools that participated in the trial. The findings are reported in four research briefs; this is the fourth of those briefs. 

Key Findings

  • Accelerometer data showed that Playworks had a positive impact on students’ physical activity during recess. Students in treatment schools engaged in physical activity during recess that was, on average, more intense than the physical activity engaged in by control students. Moreover, students in treatment schools spent significantly more time engaged in vigorous physical activity at recess than students in control schools. 

  • The main recess activity in which students were observed to be engaged was less likely to be a sedentary activity (such as sitting and talking) in treatment schools, compared with control schools. 

  • Playworks had an impact on the extent to which recess activities were organized by adults. The percentage of recess activities that were organized by school staff (or a Playworks coach, in the case of treatment schools) was significantly higher in treatment schools than in control schools. A significantly higher percentage of students in treatment schools, compared with control schools, also reported that adults helped them play games and sports “sometimes” or “a lot” during recess.

  • Teachers in treatment schools reported better recess behavior and readiness for class than teachers in control schools. 

  • A higher percentage of teachers in treatment schools, compared with control schools, agreed or strongly agreed that their students enjoyed adult-organized activities at recess and felt ownership over their activities during recess.

Learn More About


Video: Scaling Playworks

Changing Social Norms
Changing Social Norms