A phenomenographic study on the concept images and image development of prospective secondary mathematics teachers related with some geometric concepts

The purpose of this study is to investigate prospective secondary mathematics teachers? concept images of some geometric concepts and understand the development in concept images. The participants were five prospective secondary mathematics teachers enrolled in a faculty of education department of secondary mathematics education. The current study is based on prepared teaching experiment to investigate the some geometric concept images and the image development of the participants. Tihs prepared teaching experiment is Geometry (Optional) lesson that participants take at bachelor?s degree.Five prospective secondary mathematics teachers were choosen to a purposeful sampling (Patton, 1990) and voluntarily participated in this study. Data were obtained from interviews, students? written work (tests and quiz) and classroom observations. The analysis particularly focused on identifying participants? concept images as they answered interview questions during the interviews. The whole data were analyzed considering mostly Tall and Vinner?s (1981) framework of concept image.To analyze these data, the views of student teachers were categorized, compered and commented by using phenomenographic method.In light of a huge data set, the following assertions can make in this study: when a student teacher face to manage a geometric problem involving geometric concepts, by the effects of differents education experiments, he/she makes these actions: (1) Use just their new concept images. (2) First trie to overcome problem with new concept image but if they can?t, return to old concept image. (3) Prefer using old and new concept images both during the problem solving process.What also arises from this study is when someone tries to solve a problem he/she needs to use a appropriate concept image, otherwise the target behaviour can?t be showed. Before the Optional Geometry lesson prospective teachers hadn?t exposed expected concept images for geometric concepts but after the lesson they could improve appropriate images.Keywords: Geometry Education, Geometric Concepts, Prospective Secondary Mathematics Teachers, Angle, Circle, Locus, Metric, Concept Image, Image Development.