Exam boards: Edexcel, AQA, OCR The AS Music Composition Workbook will help students gain the necessary skills and confidence to write a successful composition for AS music. It assumes a GCSE level understanding of composition, and offers a series of exercises focusing on developing musical ideas, textures, word-setting, harmonisation and orchestration. There is also detailed advice on how to write effectively for a variety of instruments and how to plan a composition.