The "Playground Physics" program combines informal, play-based, embodied learning experiences to support middle school students' engagement with and motivation to learn about complex and abstract physics concepts. This experimental design study examines the impact of "Playground Physics" on students' science motivation, classroom engagement, and physics knowledge. The study involved 24 treatment teachers using "Playground Physics" with 1,928 students, and 21 control teachers teaching their regular physics curriculum to 1,478 students. Results indicate that students of treatment teachers showed significantly greater physics knowledge at posttest than students of control teachers. No differences were noted for positive student engagement and motivation in science class. Further research is needed to understand the relationship between student engagement, motivation, and learning while using Playground Physics.