Based on data collected from 211 elementary school children in central Taiwan over four years, the role of temperament in science achievement was examined with multivariate analysis of covariance (MANCOVA) with repeated measures design. The results revealed that the students' science achievement is stable over time. The task orientation characteristics (i.e., distractibility, hyperactivity, and persistence) identified by previous research as important in mathematics and reading achievement are not consistent with the findings of this study that although the impacts of distractibility and persistence are significant, the simple effect of activity level on science achievement was not significant. However, the interaction effect of activity level and persistence is significant. Further break down analyses conducted to pursuit the interaction effect revealed that: (1) persistence has a consistent significant positive effects on all children over the years, except for the ones with high activity level (the upper 25th percentile); and (2) activity level has significant negative effects on high persistence (the upper 25th percentile) children only, and the interaction effect of activity level increases over time--the older the child the more significant the influence. Also, the tendency of approach/withdraw has significant impact on science achievement The educational implications of the findings include: (1) teachers of high activity students with high persistence may need to consider the match between children's interests and contents of instruction; (2) a good match between children's individual differences in distractibility, persistence, and approach need to be considered in contents, expectations, and interactions of the instruction. (Contains 1 figure and 3 tables.)