Teachers' awareness on combinatorics during Lesson Study discussion

This study focuses on the professional development of mathematics teachers collaborating within a Lesson Study. The research aim is to analyse how teachers’ discussion can promote professional awareness. The data have been collected from a 6-cycle Lesson Study in an Italian secondary school, centred on the introduction to combinatorics. Mason’s framework is the theoretical lens to qualitatively analyse teachers’ discussion. This enabled the observation of how teachers’ awareness of students’ combinatorial thinking emerged and led to changes in teachers’ practice. Collaborative reflection during the lesson study discussion phase appears to be critical for teacher professional development.