Secure subject knowledge and understanding allows trainees greater confidence and authority, and they are better equipped to become effective and creative teachers. This UK coursebook has been written specifically to help trainee primary teachers develop their mathematics subject knowledge. This third edition has been brought into line with the new UK Qualified Teacher Status (QTS) Standards, and reflects latest thinking from the UK Primary National Strategy and other recent initiatives. New material has been added and previous material reorganized where appropriate to increase clarity.