Early enriched math instruction in pre-K and kindergarten, especially when sustained over two years, can have a positive effect on low-income children's math skills — a strong predictor of later academic achievement, a report from MDRC finds. The report, Strengthening Children's Math Skills with Enhanced Instruction: The Impacts of Making Pre-K Count and High 5s on Kindergarten Outcomes (142 pages, PDF), assessed two programs in New York City: Making Pre-K Count, which provided evidence-based early math curriculum and associated professional development, and High 5s, which combined the Making Pre-K curriculum with supplemental small-group math clubs in kindergarten. The studies found that Making Pre-K Count had positive effects on kindergartners' attitudes toward math and the equivalent of about two months' greater growth in working memory skills than the control group but had no consistently statistically significant impact on math skills. Children who participated in High 5s following Making Pre-K Count showed 2.5 months of growth over those who participated only in Making Pre-K Count and 4.2 months of growth in neither program. Funded by the Robin Hood, Heising-Simons, Overdeck Family, and Richard W. Goldman Family foundations, the report also found that early math enrichment interventions also can improve executive function skills, although it remains to be seen whether the positive effects will persist over time.