Abstract

Number sense refers to the ability to read numbers and understand numerical magnitudes and their relations, and is a foundational skill for math learning. This study examined 1st (n=47) and 2nd (n=34) graders’ number sense acuity and their mental representation and problem-solving strategies using a numberline estimation (NLE) task. First graders completed the 0-100 NLE task and 2nd graders completed both the 0-100 and 0-1000 NLE tasks. Results showed that 2nd graders are more precise when representing numbers on the numberline than 1st graders. Additionally, 2nd graders applied more benchmark-based strategies (e.g., midpoint) in the NLE task than 1st graders. Finally, a linear model was found to be more suited for depicting the patterns of 1st and 2nd graders’ numerical estimates in the 0-100 and 0-1000 NLE tasks than a logarithmic one. Taken together, these findings suggest that as students grow older, their number sense and problem-solving strategies tend to be increasingly articulate and that the linearity of their mental representation becomes more obvious. Moreover, the high precision and linearity of numerical estimates in the current study can be interpreted as reflecting a positive influence of the transparency of the base-ten number structure in the Korean language.