Explaining the relationship between number line estimation and mathematical achievement: The role of visuomotor integration and visuospatial skills

Performance on number line tasks, typically used as a measure of numerical representations, are reliably related to children’s mathematical achievement. However, recent debate has questioned what precisely performance on the number line estimation task measures. Specifically, there has been a suggestion that this task may not only measure numerical representations but also proportional judgement skills; if this is the case, then individual differences in visuo-spatial skills, not just the precision of numerical representations, may explain the relationship between number line estimation and mathematical achievement. The current study investigated the relationships among visuo-spatial skills, visuo-motor integration, number line estimation and mathematical achievement. Seventy-seven children were assessed using a number line estimation task, a standardised measure of mathematical achievement and tests of visuo-spatial skills and visuo-motor integration. The majority of measures were significantly correlated. Additionally, the relationship between one metric from the number line estimation task (R2LIN) and mathematical achievement was fully explained by visuo-motor integration and visuo-spatial skill competency. These results have important implications for understanding what the number line task measures as well as the choice of number line metric for research purposes.