Specific Contributions of Basic Numerical Skills and Working Memory to Mathematics Skills in Primary School

The development of mathematics skills is driven by domain-specific and domain-general cognitive predictors, like non-symbolic and symbolic numerical skills and working memory (WM), respectively. However, differential and potentially changing contributions of these predictors across primary school years have hardly been investigated jointly. Therefore, we assessed 486 German primary school children from first to fourth grade (i.e., 6 to 11 years old) on (non-)symbolic magnitude comparison, approximate addition, number line estimation, WM, nonverbal reasoning, and their mathematics skills in a cross-sectional study. Results of a multi-group path model indicated that number line estimation and WM were significant predictors of mathematics skills in all grade levels, and nonverbal reasoning was a significant predictor of mathematics skills in first, third, and fourth grade. Pairwise comparison of path coefficients further revealed that contributions of number line estimation were significantly stronger in third grade than in first and second grade. In sum, these results suggest that complex symbolic numerical skills and WM contribute to the development of mathematics skills in primary school, potentially reflecting effects of formal mathematics instruction.