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This paper is mainly methodological. It concerns the study of the ways teachers intervene in small groups carrying out a collaborative activity in physics. This study is developed from a point of view focused on knowledge at stake. Studies of this kind of teachers’ interventions often lead to divergent conclusions on the nature of the interventions deemed effective for both the completion of the task and learning. We believe that much of these differences may be related to the very different nature of the situations in which the teacher intervenes in small groups. Therefore, we propose a method that associates in the analyses the kinds of interactions teacher – students with the situations they are developed in. This method includes the use of different timescales. It combines an analytical approach of the didactic action considered at a microscopic scale, and a holistic approach of this action considered at a higher scale, each one being based on specific theoretical tools. We illustrate its implementation on an activity related to periodic phenomena in the tenth grade. The discussion addresses the relevance of the proposed method and the specificities of each of its approaches as well as the validity of the results.