Vol. 23 Num. 2 (2003) David Pimm Editorial2 Marion Walter Looking at a pizza with a mathematical eye3 Ana de Carvalho , Tania Cabral Teacher and students: setting up the transference11 Maria G. Bartolini Bussi , Mara Boni Instruments for semiotic mediation in primary school classrooms15 Jeremy Kilpatrick Twenty years of French didactique viewed from the United States23 Mellony Graven Teacher learning as changing meaning, practice, community, identity and confidence: the story of Ivan28 Richard Barwell Linguistic discrimination: an issue for research in mathematics education37 Josep Gascón From the cognitive to the epistemological programme in the didactics of mathematics: two incommensurable scientific research programmes?44