almost unknown to the French-speaking world ten years ago, the term ‘lesson study’ or the collective lesson study (Clivaz, 2018; Miyakawa -Winslow, (2009) just started to emerge in education sciences, particularly in educational training institutions, in Roman Switzerland as well as in France. From a research point of view, the lesson study is akin to research and action; from the point of view of training, it is akin to continuing training or professional development. Originating in Japan, extradited and developed in the United States, then in England, Sweden, Hong Kong and the rest of the world, the latter remains an unfamiliar concept in our cultures and its characteristics vary (Buchard -Martin, 2017). The research questions and studies the lesson study from different points of view: impact on educational teams, collaborative arrangements, training and professional development, its effectiveness on student learning, and from the point of view of school management (Progin et al., 2021). More specifically, the lesson study is a cyclical process that goes through different steps: (1) the choice of a topic and the definition of learning objectives; (2) preparing for planning what is commonly referred to as research lesson; (3) its implementation and observation; (4) the analysis and evaluation of this teaching time, which may be subject to iteration; 5) to the distribution and sharing of documentation on the work carried out (Martin and Clerc-Georgy, 2017). This type of approach places all actors and actors in the system in a similar posture, that is to say, that of professionals who analyse teaching and learning. Each person participates with his or her field of expertise, which helps to enrich the analyses. The lesson study aims in particular at the professional development of teachers and teachers, in relation to apprenticeships for all pupils. The Symposium brings together actors and actors from different backgrounds in the field of French-speaking research (teachers and teachers, trainers and trainers, researchers and researchers, school executives). It aims to present and share different practices. A few questions will guide our reflections: what are the tools created as part of the lesson study, for what purposes, for what purposes? What are the strengths and limitations of the latter? In other words, what are the tests carried out, with what results? Research conducted by the authors of the symposium is akin to new forms of research (research and training) and helps to identify challenges for a school of tomorrow.