Abstract
This paper contributes to the research agenda on intervention studies and their impact on learning outcomes. It focuses on early grade mathematics in South Africa by drawing on four years of cross-sectional data (n = 5,724) from treatment and control primary schools in the same district in Gauteng. Early Grade Mathematics Assessments (EGMA) were administered to a random selection of learners in both school groups over a period of 4 years. Findings show a statistically significant difference in mean attainment on the EGMA assessment in the JumpStart schools (effect size of 0.52) and with further improvements evident after 3 years (effect size of 0.94). These effect sizes are compared to existing South African studies as well as meta-analysis of studies from low- and middle-income countries. Benchmarks for EGMA raw score attainment at Grade level in the Ekurhuleni South district of Gauteng (n = 2,625) are provided.