Reinforced racial integration in the first grade: a study in generalization.

First-graders earned stickers and praise for sitting with a 'new friend' at lunch. The team picked new friends to mix races. They watched lunch and recess to see if the lunch gains carried over to free-play.

Reinforcement quickly raised integrated sitting at lunch. Recess play also became more mixed, but the jump was smaller and bounced around more. Some kids kept the new pattern; others needed booster days.

Oh-Young et al. (2015) later showed the same thing across 24 studies: integrated classrooms lift both grades and social skills. Jones et al. (1992) added brief social-skills groups and saw even bigger recess gains for kids with autism. Syriopoulou-Delli et al. (2012) pushed further, teaching kids to start games so the play lasted after staff left. The 1973 lunch trick is still the simplest first step; later papers just bolt on extra layers.

You can start tomorrow: pick two kids who rarely sit together, tape their names side-by-side on a lunch chart, and hand out stickers when they do. Five days may be enough to see recess spillover. If the play fades, add the initiation drills that Syriopoulou-Delli et al. (2012) used. The whole intervention costs one roll of stickers and a marker.