Emma Castelnuovo: three key ideas

This paper focuses on three key ideas that underpinned the pedagogical research and teaching activity of Emma Castelnuovo over a period going from 1944 to 2014:1. teacher-researcher;2. dynamic geometry;3. real-world mathematics education.The paper will seek to find answers to various questions about previous ideas, among which: Where do these ideas come from? How, when and where are they implemented in secondary school teaching? Can we envisage their future development?