抄録
The purpose of this study is to examine the meaning of Number Sense and a framework for describing it. It reveals that the meaning of a for Numbers is related to the following issues: meaning, property, and relation of numbers, and of the operation on numbers. However, those issues are situation-specific. In constructing the framework, the process begins with determining some aspects of students' activities, and analyzing students' activities using those aspects, then examining through those aspects closely. The framework suggests five aspects of students' activity should be considered: "object", "situation", "aim", "method", and "validation", "Method" and "validation" can be discussed in terms of mathematical appropriateness and appropriateness which is related to the aim of a particular situation. Moreover, for the purpose of describing Number Sense, the framework also suggests that we should consider the relationship between the five aspects. Specifically, we should also examine the other three aspects of students' activities: "object", "situation", and "aim".
