Managing the sharing of solutions, procedures, representations and ideas among pupils after solving a mathematical problem presents challenges at the collective construction of knowledge and organisational levels. This critical moment, known as "whole class discussion" in English, "mise en commun" in French, "discussões coletivas" in Portuguese, and "neriage" in Japanese, plays diverse roles in different mathematics classroom cultures.

Within the context of lesson study, this moment sometimes serves as the focal point for the lesson study research question. Our symposium aims to describe and analyse the experiences of lesson study groups in Portugal, Switzerland, and Singapore. By comparing their approaches to "whole class discussion" with the Japanese "neriage," we seek to gain a deeper understanding of the challenges inherent in this moment and its potential to enhance students' learning outcomes.