Improving Mathematics Teachers' Professional Knowledge through Lesson Study in Secondary Schools

The main purpose of the study was to understand how engaging in lesson study can improve the professional knowledge of mathematics teachers in secondary schools to support students’ learning better. The research was conducted in Jimma City, Ethiopia, and employed design-based research with qualitative and quantitative data collected from two secondary schools and 12 mathematics teachers. A purposive sampling technique was used to select participants. The main data sources were interviews, observations, document analysis, and questionnaires. Qualitative data were analyzed thematically using the Atlas-ti qualitative data analysis software. Quantitative data were analyzed using mean, standard deviation, median, and the Wilcoxon Signed Rank test. The study’s findings revealed that engaging in lesson study boosted mathematics teachers’ knowledge of students and their learning process; broadened teachers’ understanding of content; and deepened teachers’ pedagogical content knowledge. Lesson study was found to be a potent model to improve mathematics teachers’ professional knowledge. Implementing lesson study with design-based research might be a vital lesson to be adopted by other African countries in improving mathematics teachers’ professional knowledge, based on their country’s specific school contexts. Future research should also investigate the impact of improved teachers’ professional knowledge on teachers’ instructional practices and students’ mathematics learning outcomes.