concepts of geometric figures

包摂関係

inclusion relations

理解

understanding

定義指導

teaching definitions

概念イメージ

concept image

The purpose of this study is to show the transition of students' understanding of inclusion relations between geometric figures through the lessons which adopt the situation of discussing about definitions of geometric figures. First it clarifies that teaching definitions of geometric figures promotes concept formation of these figures in this study. Second the factors of teaching definitions of geometric figures are pointed out based on the results of the previous studies. Third the lessons which adopt the situation of discussing about definitions of geometric figures were given and the survey of understanding of inclusion relations between geometric figures before and after the lessons administered and the results of the survey were considered. It follows from what has been said that the teaching definitions effects students' understanding of inclusion relations between squares and rectangles, rectangles or rhombi and parallelograms, regular triangles and isosceles, right isosceles and isosceles, however, students who understood the definitions of geometric figures appropriately was not able to use the inclusion relations in order to select figures that are consistent to their concept image of geometric figures.