Lesson study application for developing prospective mathematics teachers' pedagogical content knowledge about decimal notation

In order for teachers to be able to teach effectively, they should be aware of the situations that may occur in the classroom, prepare a lesson plan suitable for the class, and have sufficient field knowledge on the subject. In this context, teachers and pre-service teachers must have sufficient pedagogical content knowledge. From this point of view, the research aims to examine the effect of lesson study application on the development of pedagogical content knowledge of prospective mathematics teachers about decimal notation. In the research, the change in the knowledge of the pedagogical content knowledge components, knowing the student and teaching strategies of the pre-service teachers before and after the lesson study was examined. In the research based on the qualitative approach, the action research method was used. The study group consists of five prospective mathematics teachers studying in the last year of the secondary school mathematics teaching program at a state university in the Western Black Sea region. As data collection tools, The Content Knowledge Test, the Recognition of the Student Test, and the Knowledge of Instructional Strategies Test were used. In addition, the data collection process was enriched with different data collection tools such as video recordings of the lesson study, field notes on reflective discussions in each cycle, interview and observation. The data were analyzed thematically, and content and descriptive analysis techniques were used. As a result of the research, it was revealed that the lesson study practice had a positive effect on the development of the pedagogical content knowledge of the pre-service teachers about decimal notation, and the deficiencies and mistakes of the pre-service teachers in the pedagogical content knowledge components, getting to know the student and teaching strategy were eliminated. In addition, it was revealed that pre-service teachers stated that they saw positive contributions to their professional development in reflective discussions in lesson study cycles.