Diagrams and mathematical events: Encountering spatio-temporal relationships with graphing technology

International audienceThis paper presents the diagrammatic activity of some secondary school students exploring motion through graphing technology, which captures a pair of space-time graphs on a single Cartesian plane. Focus is on a written task about the connections between two imaginary movements and (between) the corresponding graphs. Drawing on a vision that conceives mathematical thinking as a place of events instead of objects, we discuss three unexpected diagrams for how they bring forth inventive and speculative possibilities for learners to encounter and problematize spatio-temporal relationships, rather than seeing them as ways of being mistaken