The purpose of this study was to investigate pedagogical content knowledge (PCK) of pre-service secondary mathematics teachers using a teaching unit from solid objects. This is a case study where pre-service mathematics teachers’ PCK is investigated in detail. The study group consists of three pre-service secondary mathematics teachers in their final year. The data of the study are obtained from semi-structured interviews with students, lesson plans prepared by the students, and video recordings of instructional applications. A framework of PCK formed using the literature and is used in the data analysis. Results of the analyses showed that pre-service teachers could emphasize the necessity of moving from a plane object to solid objects and be able to establish relationships with their prior knowledge. Activities prepared by the participants indicated that they used volume, dimension, projection, and one-to-one correspondence of dots, identified the matched objects as the critical points, and could give the definitions of solid objects. In addition, it was found that pre-service teachers utilized visual and concrete materials very often in order for students to better perceive solid objects which indicated their use of different mathematical demonstrations. It was found that participating pre-service teachers did not pay attention to possible student misconceptions about the topics and they did not refer to alternative assessment techniques to determine student learning. In the light of the findings of the study, it is suggested that in the process of preparing pre-service teachers they should be helped to gain PCK and also provided with instructional application experiences in which they can demonstrate their PCK.

Key words: Pedagogical content knowledge, solid objects, pre-service mathematics teachers.