Comparative analysis of studies related to Van Hiele geometric thinking levels

Geometry is an important part of the mathematics curriculum. The van Hiele Theory, which is widely used and directs geometry education, was introduced by the couple Dina van Hiele and Pierre van Hiele in 1957. Considering that van Hiele Theory has become the focus of geometry teaching and that the education reforms of countries are shaped around this theory, it is thought that the theory has great importance. In this context, with this study, it is aimed to describe van Hiele Theory in detail, to synthesize the results of national and international research on the theory, to make comparisons with a critical and holistic perspective, to compare the level naming and numbering system used in both fields, to measure van Hiele's geometric thinking levels. It is aimed to examine the evaluation methods used in both areas in detail, to make relevant interviews and to present in detail the effects of theory-based teaching practices on students' geometric thinking levels. In this study, in which thematic content analysis method was used, the data obtained for the measurement tool were also supported by a case study. Within the scope of the research, 86 studies in Turkish and 81 studies in English were determined to be analyzed, and semi-structured interviews were conducted with 41 teacher candidates and 23 postgraduate teachers. The data obtained from the study were analyzed using the qualitative data analysis method. When the study findings are examined, it is seen that studies are conducted to determine the effect of different learning environments on geometric thinking levels in both areas, experimental studies are emphasized, a larger sample group is studied in the international literature compared to Turkey, tests are preferred as data collection tools, and different learning environments are used to determine the geometrical thinking levels of students. It has been concluded that it is effective in increasing the level of thinking. When the findings were examined, it was seen that the naming and numbering given to the levels in both domains differed greatly. In addition, when the measurement-evaluation tools in both areas were examined, it was concluded that the tools in the international area had more diversity. In addition, when the teaching practices of the studies in the national and international literature were examined, it was concluded that the most preferred one from both literatures was the design of teaching using dynamic geometry software in the courses. Based on the results obtained in the study, some suggestions were made.