An Investigation into Students' Understandings of Class Inclusion Concepts in Geometry

Abstract

This study investigated students' understandings of class inclusion concepts in Geometry. The purpose was to identify a developmental pathway leading to an understanding of the interrelationships among two-dimensional figures and their properties. The design involved a tightly focused investigation of the manner in which geometrical class inclusion concepts evolve, in particular, relationships among triangle and quadrilateral figures, and relationships among their properties. Empirical evidence is provided to explain the difficulties students face in understanding of class inclusion notions. This evidence has theoretical as well as practical implications.