Within the National Curriculum, teacher assessment is help up as good professional practice - but the only official guidance is that teachers should look to and record their pupils' "significant achievement". Yet what is significant achievement? And is it the same for each child? This text is one in a series which seeks to explain the idea of significant achievement, and explores the implications for the planning, assessment and record-keeping cycle throughout the primary school. It aims to put significant achievement, and how to foster it, within a subject context, and tells teachers how to start tracking significant achievement in their own classrooms. It provides examples and advice for defining and recognizing what constitutes achievement for each child, and guidance on how to use such "milestones" formatively, as a basis for teaching. It also highlights what constitutes "progression", in terms which link with but go beyond the National Curriculum - including physical and social skills, attitude development, "concept clicking" and process skills.