This article reports on a particular aspect of a PhD study into pupil composing in music classrooms with information and communications technology (ICT). Two case studies based in England investigated the work of two groups of pupils in different phases of education, one aged 12-13 (secondary) and the other 10-11 (primary). A theoretical lens that was utilized to illuminate a specific aspect of the learning design was that of proscription, which not only allowed a detailed investigation of pupils' generative activity to be made, but also revealed aspects about the learning environment that often remain tacit and hence unexplored. A key outcome of the study was the suggestion that the notion of proscription be extended to one of providing the possibility of moving beyond given constraints to compose music that lies outside their boundaries. (Contains 3 notes, 3 tables and 2 figures.)