Number line estimation and mental addition: Examining the potential roles of language and education

• Chinese kindergartners’ 0–100 estimates and second graders’ 0–1000 number line estimates are linear.
• Chinese children’s number line estimates are more linear than Chinese-American’s.
• Chinese children’s complex addition is more accurate than Chinese-American’s.
• There was a two-year period between linear 0–100 estimates and linear 0–1000 ones.

This study investigated the relative importance of language and education to the development of numerical knowledge. Consistent with previous research suggesting that counting systems that transparently reflect the base-10 system facilitate an understanding of numerical concepts, Chinese and Chinese American kindergartners’ and second graders’ number line estimation (0–100 and 0–1000) was 1 to 2 years more advanced than that of American children tested in previous studies. However, Chinese children performed better than their Chinese American peers, who were fluent in Chinese but had been educated in America, at kindergarten on 0–100 number lines, at second grade on 0–1000 number lines, and at both time points on complex addition problems. Overall, the pattern of findings suggests that educational approach may have a greater influence on numerical development than the linguistic structure of the counting system. The findings also demonstrate that, despite generating accurate estimates of numerical magnitude on 0–100 number lines earlier, it still takes Chinese children approximately 2 years to demonstrate accurate estimates on 0–1000 number lines, which raises questions about how to promote the mapping of knowledge across numerical scales.