Co-ordinated Science is a three or two-year course leading to double certification at GCSE, developed and trialled by Suffolk LEA, approved by SEAC, and adopted by 78 LEAs in England and Wales by 1990. The course is currently being revised in line with the National Curriculum in science and the new GCSE criteria. The course consists of nine units per year, three each in biology, chemistry and physics. The component publications of the course are an introductory book designed to meet the National Curriculum for the end of Key Stage 3, an optional introductory-level book covering biology, chemistry and physics activities, and an assessment pack offering a set of photocopiable masters which provide a mix of tasks for six of the nine units and end-of-unit tests for the remaining three units. The assessment pack is aimed at levels 3-7 of Attainment Targets 1-17. This publication is the introductory book, National Curriculum edition. Its reference section has been improved for this edition.