Lesson study as a professional development framework to support an exploratory approach

International audienceOur aim is to present the views of a group of basic education teachers involved in a lesson study as they discuss the features of tasks, students’ difficulties, and how to conduct exploratory work about rational numbers in the mathematics classroom. Data collection was made through audio/video recording of the lesson study sessions, teachers’ written reflections, individual and group interviews, and a researcher’s journal. The results show that the teachers developed a vocabulary to speak about mathematics tasks, and developed an appreciation for students’ reasoning processes such as generalizing and justifying as well as for classroom discussions as important moments for argumentation and negotiation of meanings