Research into Relationship between the Computational Estimation Ability and Strategy and the Mental Computation Ability : Analysis of the Fourth, Fifth, and Sixth Graders in Japan

The purpose of this research is to obtain performance data on the computational estimation and mental computation skills of Japanese students in grades 4, 5, and 6, to clear effects of the teaching and learning of rounded numbers and rounding strategies on computational estimation, and to inquire the relationship between computational estimation ability (CEA), strategy (CES) and mental computation ability (MCA). This paper shows that: (1) the teaching and learning has strong effects on computational estimation containing only numerical data positively and on computational estimation in problematic situations negatively; and (2) there are significant relationships both between CEA and MCA, and CEA and CES, but there is no significant relationship between CES and MCA. These results suggest that the reasonable and efficient computational estimation requires flexible rounding of numbers based on sound number sense as well as mental computation ability