The focus of this research was the conduct and analysis of six hours of clinical interviews with sixth and ninth grade students to investigate how they learn geometry in light of the van Hiele model. In chapter 1 an overview of the project and its four major goals is given. The theoretical model is described in chapter 2. In chapter 3 the…

The objectives of this study were to: (1) develop a working model based on Pierre van Hiele and Dina van Hiele-Geldof's five levels of thought development in geometry; (2) characterize the thinking in geometry of sixth (N=16) and ninth (N=16) graders in terms of these levels (examining at what level they are at, if they show potential for progress…