Hilary Koll (Author) Hilary Koll is a part-time Mathematics Co-ordinator and teacher of children in Berkshire Primary school. She works as a Lecturer in Mathematics Education at the University of Reading on undergraduate, post-graduate and in-service training courses. Steve Mills (Author) Steve Mills began his career as a primary school teacher before becoming a Lecturer in Mathematics education at the University of Reading, working with students in initial teacher training, and providing INSET for schools. He is now a full-time writer and consultant in mathematics education.