Under-achievement in maths is a growing concern for many teachers. This book shows how a developmental approach to teaching maths can help to both identify difficulties and raise children's achievement. Beginning with the early years, age-focused chapters look at the knowledge children develop outside school; how teachers can assess and build on that knowledge; children's misunderstandings in maths, and how to remedy these. Each chapter is closely linked to the requirements of the National Numeracy Strategy, and example lesson plans and activities are included detailing ways of using recommended strategies within the numeracy hour.