Executive functions and spatial/relational reasoning relate to individual differences in fraction understanding

Studies have shown the importance of executive functions (EFs) and spatial and relational reasoning for fraction understanding; however, few studies have examined them simultaneously. We analyzed two datasets to examine how these domain-general skills contribute to performance in fraction magnitude comparison and number line estimation tasks. In Study 1, third graders (n = 84) completed working memory and cognitive flexibility tasks, a standardized test of relational reasoning, a whole number line estimation task, and two fraction tasks-fraction comparison and estimation. Cluster analysis showed that participants formed two clusters based on fraction task performance, with one cluster outperforming the other on both tasks; logistic regression showed that working memory and prior knowledge predicted the odds of being classified to the higher-performing cluster. In Study 2, we applied the same analysis to sixth graders (n = 57), who completed an inhibitory control task, patterning word problems, a standardized math achievement test, and fraction tasks. Results showed the same higher-performing and lower-performing clusters, with prior knowledge (achievement test) as the significant predictor. Results provide initial evidence regarding the joint roles of these skills; however, given the heterogeneity in the measures and designs, which limit direct comparison across our samples, more research is needed to clarify how domain-general and domain-specific skills contribute to fraction understanding.