There is a new best evidence in brief with this time a very important paragraph at the end of this summary of an article on early math program (italics by me):
Pre-K Mathematics is a supplementary mathematics curriculum for pre-k children. It focuses on the pre-k classroom and home learning environments of young children, especially those from families experiencing economic hardship. Activities aim to support mathematical development by providing learning opportunities to increase children’s informal mathematical knowledge.In an article published in Evaluation Review , Jaime Thomas and colleagues report on a cluster-randomized control trial of the scale-up of Pre-K Mathematics in 140 schools in California (70 intervention schools, 70 control). The post-test measured outcomes on the Early Childhood Longitudinal Study, Birth Cohort Mathematics Assessment (ECLS-B) and the Test of Early Mathematics Ability (TEMA-3) at the end of the pre-k year. Results showed that Pre-K Mathematics had positive and significant effects, with an effect size of +0.30 on the ECLS-B and +0.23 on the TEMA-3.The authors consider how these results differ from previous, smaller studies of the efficacy and effectiveness of Pre-K Mathematics. They find that effect sizes were usually larger in the earlier studies. As studies became larger, more heterogeneous, and less controlled, they tended to yield smaller results.