--- - |2 Summary We examined the effect of distributed practice on the mathematical performance of third and seventh graders (N = 213) in school. Students first received an introduction to a mathematical topic, derived from their curriculum. Thereafter, they practiced in one of two conditions. In the massed condition, they worked on three practice sets in one day. In the distributed condition, they worked on one practice set per day for three consecutive days. Bayesian analyses of the performance in two follow‐up tests one and six weeks after the last practice set revealed a positive effect of distributed practice as compared to massed practice in Grade 7. In Grade 3, a positive effect of distributed practice was supported by the data only in the test one week after the last practice set. The results suggest that distributed practice is a powerful learning tool for both elementary and secondary school students in the classroom. - Applied Cognitive Psychology, Volume 0, Issue ja, -Not available-.