One of the fundamental problems in education is that of applying skills and knowledge which learners have gained in one context to problems they encounter in another. This is particularly so in mathematics, where the problems encountered by learners in applying mathematical knowledge are well documented. Using and applying mathematics has been a central component of the National Curriculum in mathematics. However, the National Numeracy Strategy has adopted a new approach, in which 'using and applying' is integrated throughout the mathematics curriculum. This book aims to help teachers develop their understanding and practice in this crucial area. It is based on the findings of a major research study, funded by the Nuffield Foundation, in which a group of primary teachers worked closely with the research team to develop their thinking and practice. The book provides a clear conceptual analysis of the problem of application, together with extensive examples of ways in which teachers can address it in their classrooms at Key Stages 1 and 2. A novel feature of the book is that it includes first-hand accounts of practice in Japanese classrooms, and outlines what teachers in the UK and elsewhere may learn from Japanese methods.