Science teacher candidates' mental models in geometric optics with three-tired diagnostic test

In physics lessons, abstract concepts come to the forefront in many subjects. For this reason, it is necessary to make the concepts concrete and to facilitate the understanding. For this purpose, conceptual texts are used in the courses with various visualizations and visuals. The main purpose of this study was to determine the prospective science teachers' mental model of geometric optics by using the three-tired diagnostic test for the Geomemetric Optics taken from the literatüre. Three-tired diagnostic tests related to geometric optics taken from the literature were used as a data collection tool in the study and mental modeling levels of teacher candidates' geometrical optics were determined by these three step diagnostic tests. The sample of the study was fifty science teacher candidates who were in the third grade of Erzurum Atatürk University Kazim Karabekir Education Faculty. The data were analyzed using an iterative, nonlinear constant comparison method in which prior knowledge, and reasoning strategies were identified within each task. As a result of the study, it was determined that the teacher candidates are generally at a sufficient level to express the conceptual knowledge about the reflection of the geometric optic unit but they can not determine conceptual knowledge of drawings. It has been understood that teacher candidates were inadequate not only in expressing conceptual knowledge but also in drawing special rays and image formation of conceptual knowledge regarding the refraction of light. In addition, it has been determined that the science teachers candidates who make up the sample could not establish the cause and effect relation with the nature of the light by the three tired diagnostic test. It has been suggested to determine the prospective science teachers' preliminary knowledge, misconceptions and misunderstandings about geometric optics and to make the teaching in this direction. Research should be done to develop the teacher candidates' imagination skills and make them ability to shape the concepts.