School-based professional development interventions: The effects of a lesson study approach for mathematics teachers

School-based professional development interventions are regarded as one of the most efficient ways to facilitate teacher learning. However, the available evidence supporting their effectiveness is limited. This paper assesses and seeks to understand the effects of a school-based professional development intervention that uses Lesson Study to foster improvements in the teaching and learning of primary and secondary school mathematics. Retrospective pre-testing and semi-structured interviews reveal that teachers perceive changes in their curriculum decisions and instructional practices after participating in the intervention. Furthermore, the findings suggest that collaboration, peer observation and critical reflection are essential components in assisting teachers with the selection and implementation of effective teaching strategies. The findings suggest that school-based professional development interventions can be effective in improving teachers' instructional practices and curriculum decisions. The authors therefore recommend a shift towards more situated, collaborative and school-based professional development approaches for teachers.