Concept definitions and concept images of middle school 7th grade students related to the concept of angle

Geometry is a field where individuals can concretely see the areas of use of mathematics in daily life. The fact that angle is one of the building blocks of geometry and is included in many geometry topics reveals that students need to learn this concept correctly. Therefore, the study aimed to determine the students' concept definition, concept images and the association between concept definition and concept image regarding the concept of angle. In the study in which the qualitative research method was adopted, a form consisting of open-ended questions was prepared by taking into account most of the learning outcomes regarding the concept of angle up to the 7th grade. The form was applied to 168 7th grade students studying in a state middle school and clinical interviews were conducted with 9 selected participants through the form. The written answers of the participants and the data obtained from the clinical interviews were analyzed using qualitative data analysis and interpreted within the framework of concept definition and concept image. In the study, it was observed that the participants had incorrect or incomplete images regarding the concept of angle and produced concept definitions from concept images. The participants could not define angle formally, confused angle with angle measurement and mostly emphasized the dimensional feature of the angle. It was also revealed that the participants had difficulty using the concept of angle in problem situations. Keywords: Concept definition, Concept image, Angle.