Fifty-one children (28 boys and 23 girls) aged 4–5 years from 9 different Kindergartens completed a child mathematics assessment (CMA, Klein, 1999; Cronbach’α = 0.92) in the first and second attempts; however, only 48 children completed the assessment in the third attempt. Children who passed in 1 item earned 1 point. Fifty-one mothers (25 with above high school education and 26 with high school and below high school education) were asked to predict their children’s total points in the CMA presented in the questionnaire only at the second attempt.

An ANOVA revealed significant difference between mothers’ assessments of boys and girls (F(1, 47) = 8.98, p < 0.05), no significant difference in assessments of mothers with different educational levels (F(1, 47) = 1.22, p > 0.05), and no significant interaction between gender and mother’s educational level (F(1, 47) = 0.14, p > 0.05). Maternal assessments and children’s scores (the second test) did not correlate significantly (r = 0.23, p > 0.05). Further, 94% mothers gave inconsistent scores ranging from 1~18 points. An ANOVA with 2 (gender) × 2 (education) × 3 (children’s performance level in the first test) revealed that only the main effect of children’s performance level was significant (F(2, 40) = 4.67, p < 0.05). The maternal assessment accuracy and children’s scores (the second test) correlated significantly (r＝0.79, p < 0.001). When the children’s scores in the first and second tests were controlled, an ANCOVA revealed that the maternal assessment accuracy significantly predicted the development of children’s mathematical abilities (the third test) (F(2, 42) = 6.71, p < 0.01).

In summary, mothers tend to overestimate their children’s mathematical ability. Different from maternal educational level and children’s gender, the maternal assessment accuracy varied with the children’s previous mathematical performance, and mothers more accurately assessed children with high mathematical ability. The maternal assessment accuracy was positively related to the children’s performance; moreover, overestimation by mothers to some extent could be propitious to promote their children’s mathematical development later. All these results suggest that the educators should be aware of the importance of scientific assessments of children’s mathematical abilities and adjust their thoughts and behaviors; thus, the development of children’s mathematical abilities was facilitated