This paper reports on the use of the concept of scheme as one of the references for analyzing the process of making out the meaning of relative time. It is part of the current perspective that discusses the inclusion of Modern Physics topics in high school education; the paper investigates the conditions for such inclusion to occur. To this end, a didactic sequence was produced based on the transition between the key concepts of Classical Mechanics and the Special Theory of Relativity, where one of the central points was the discussion of the influence of the reference frame in the study of motion. The research activities lasted 16 classroom hours in a third-grade year high school and were quite diverse, with lectures, group discussions, open problem-solving, and thought experiments. We analyzed, in this paper, episodes of verbal interaction and written activities of the students related to the concept of reference frame and its influence on the notion of relative time. The theoretical framework used for the analysis of the students' productions was the Theory of Conceptual Fields, which was supported by the content analysis technique. Different operational invariants were identified in the students' schema of motion and time. We concluded our research by indicating that there must be a reciprocal assimilation between the schema of time and motion for the students to be able to propose correct answers to problems in Mechanics.

scheme, operational invariants, subject in action, motion, time