Yves Chevallard (1946–2026)

Yves Chevallard passed away on 16 March 2026. He was 79 years old. Born in Tunis, he trained at the École normale supérieure in Paris, where he earned an agrégation de mathématiques. He went on to become a professor at Aix-Marseille Université, and it was there, over several decades, that he built one of the most ambitious research programmes in the didactics of mathematics. A 1976 encounter with Guy Brousseau at the IREM in Bordeaux defined his path.

His first major contribution was the theory of didactic transposition, developed through the 1980s and crystallised in La Transposition didactique: du savoir savant au savoir enseigné (1985). The question at its core was deceptively simple: what happens to knowledge when it moves from the research context where it was created into the classroom where it is taught? The answer, Chevallard argued, was that it is transformed far more deeply than anyone usually admits. From that insight, he went on to develop the Anthropological Theory of the Didactic (ATD), a framework that pushed the study of teaching and learning into the territory of culture, institutions, and the social life of knowledge. The International Commission on Mathematical Instruction awarded him the Hans Freudenthal Medal for that work in 2009.

His connection with the CRM was long. He first came in January 1991 for a research stay, returned in December 1994 for a seminar alongside Miguel de Guzmán, Guy Brousseau, and Paolo Boero, and went on to participate in the 3rd International Congress on the ATD (January 2010), an Intensive Research Programme (June–July 2019), and the 7th and 8th CITAD (June 2022 and January 2026). The last of those was held here just two months ago.

He left behind a body of work that asks hard questions about what school mathematics is actually for. In a 2017 article for the Gaceta de la RSME, he argued that mathematics is taught as a treasure to be visited, not used, and that most students sense, correctly, that it was never really meant for them. He spent his life trying to fix that.

Our deepest condolences go to his family, his colleagues, and the community of researchers who carried his work forward alongside him.