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This paper develops both a method for analyzing the didactic contract involving different timescales and the description of the contract associated with physics teaching in the tenth grade. In our analyses we use the joint action theory in didactics and its usual concepts (contract, milieu, transaction, and game), and we chose to associate the concept of the didactic game with the mesoscopic scale (10 to 30 minutes). A viewpoint adapted from linguistics completes our theoretical framework at the microscopic level of several seconds, based on the concept of the “act.” An intermediary scale (1 to 5 minutes) bridges the microscopic and mesoscopic levels. We developed analyses at each timescale; they show regularities in teacher-student joint action, which we interpret according to the context given by the higher timescales. These regularities enabled us to formulate rules at different timescales, formalizing the reciprocal expectations of the teacher and the students, that is to say, belonging to the didactic contract. These analyses lead us to establish two more timescales (60–90 minutes; 120–180 minutes), whose relevance for other kinds of teaching sequences remains to be seen.