'Lived resources' and mathematics teachers professional development

International audienceThe resources available for mathematics teachers now proliferate. Traditional curriculum material is complemented by online resources of several kinds: software, lesson plans, even classroom videos. Each teacher can develop an individual website; online teachers associations propose digital textbooks etc. These evolutions impact the design and use of resources, the articulation between design and use; they position the teacher as a designer. Studying these issues with a research point of view requires a specific approach. I will present here a documentational approach developed for this purpose. I will illustrate the use of this approach by case studies concerning, on the one hand, individual teachers; on the other hand, teams of teachers involved in a teacher training program using a distant platform