Teacher assessment is held 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 every child? This text is one in a series which aims to explain the idea of signficant achievement, and explores the implications for the planning, assessment and record-keeping cycle throughout the primary school. The concept of signficant achievement is particulary appropriate to early years teaching, and offers the potential for continuity in recording children's progress from nursery through to Key Stage 1 of the National Curriculum. It provides examples and advice for defining and recognizing what consitutes significant achievement in each child, and guidance on how to use such "milestones" formatively, as a basis for teaching. It also highlights what constitues "progression" in the developmental skills areas which underpin the National Curriculum - including physical and social skills, attitude development, "concept clicking" and process skills. Well-chosen examples, with commentaries, point up what is significant and why, and what the teacher should do next.