Enriching pre-service teachers’ conceptions about proof with discrete mathematics.

International audience ; The following article proposes an opening of a well-known situation coming from the theory of didactical situation (namely “The Race to 20”), leading to an ongoing open problem for mathematicians. This discrete situation is at the interplay of game theory, number theory and algorithmics. Its use in a pre-service secondary teachers’ training course aims at encouraging teachers to reflect on the mathematical activity of proof and its writing in the classroom.