Non-symbolic ratio processing and symbolic fraction processing both involve thinking about relations between two partsand relational thinking. Despite the close connections between non-symbolic ratio and symbolic fractions, previous re-search on non-symbolic ratio processing and symbolic fraction learning have proceeded separately. The current researchinvestigated whether children’s non-symbolic ratio sense support their symbolic fraction success. Using sample of 151children, we found that non-symbolic ratio sense significantly predicted fraction knowledge assessment scores and sym-bolic fraction comparison performance, but not for fraction number line estimation performance. The implications of thesefindings for theories of numerical development and for improving mathematics learning are discussed.

Fraction knowledge is not only important for later STEM related education achievement but also crucial for employmentand health. However, many children have great difficulties learning fractions. The present study examined predictorsof fraction knowledge performance in second and fifth grade, including both math-specific skills and general cognitiveabilities. Individual differences in non-symbolic ratio acuity, whole number line estimation, and auditory working memorywere significant predictors of symbolic fraction knowledge performance. Non-symbolic ratio acuity made the largestcontribution to symbolic fraction performance compared to other predictors. The implications of these findings for theoriesof numerical development and for improving mathematics learning are discussed.