Closing the Gap in Early Mathematics: Domain and Cognitive Insights from TIMSS 2023 in South Africa and Singapore.

BACKGROUND: South Africa continues to underperform in primary mathematics, yet overall mean comparisons obscure where achievement gaps are most concentrated. This study examines domain-specific patterns of mathematics achievement using data from the Trends in International Mathematics and Science Study (TIMSS) 2023, benchmarking South African Grade 5 learners against Singaporean Grade 4 learners assessed on the same TIMSS Grade 4 mathematics framework. METHODS: A quantitative secondary analysis was conducted using nationally representative TIMSS 2023 datasets comprising 10,424 South African learners from 285 schools and 6,530 Singaporean learners from 181 schools. South Africa assessed learners in Grade 5 using the TIMSS Grade 4 mathematics instruments, consistent with TIMSS procedures where curriculum exposure aligns with the benchmark framework. Mathematics achievement was analysed across content domains (Number, Measurement and Geometry, Data) and cognitive domains (Knowing, Applying, Reasoning). Weighted estimates, replicate-based variance estimation, and effect sizes (Cohen's d) were computed in accordance with IEA technical guidelines. The analysis is descriptive and comparative rather than causal. RESULTS: South African learners performed substantially below the international centre point across all domains. The largest content-domain gap relative to Singapore was observed in Measurement and Geometry, indicating pronounced weaknesses in spatial reasoning. The largest cognitive-domain gap occurred in Knowing, reflecting fragile foundational fluency. Although Applying was relatively stronger within the South African profile, it remained substantially below benchmark levels. Achievement gaps were therefore concentrated in foundational and spatial domains rather than uniformly distributed. CONCLUSIONS: Concentrated achievement gaps in foundational knowledge and geometry characterise the underperformance of primary mathematics in South Africa. The findings provide a structured diagnostic profile of domain-specific achievement disparities, highlighting the concentration of gaps in foundational knowledge and spatial reasoning.