Examination of middle school mathematics teachers' subject matter knowledge on addititon and subtraction with integers

In this research, it is aimed to examine the subject matter knowledge of middle school mathematics teachers' in the field of addition and subtraction with integers, within the scope of mathematical knowledge for teaching model. Multiple case study design was employed in this research, two mathematics teachers from two different middle schools in East Black Sea Region participated in the study. Purposive sampling is used in the selection of participants. During the application process, interviews with teachers were recorded with voice recorder and course processes were recorded with video camera. Data which were collected through in-class observations, individual pre-interviews and post-interviews with each teacher are subjected to descriptive analysis techniques. According to the results of the research the deficiencies of subject matter knowledge of the middle school mathematics teachers are mainly centered around specialized content knowledge. In the context of specialized content knowledge, it has been determined that teachers have problems in terms of meaning of addition and subtraction with integers, problems in these processes while teaching, modeling of these operations with number line and distinguishing between sign of integer and sign in modeling processes. Teachers' subject matter knowledge about the addition and subtraction with integers is an indicator that direct transfer of the essential gains which is generally adopted in mathematics teaching. Moreover, the result of this research reveals the significance of identifying and developing the subject matter knowledge of middle school mathematics teachers.