This article looks in some detail at the transcript of a mathematics lesson in exploring the nature of low-level disruption in schools. This is preceded by a brief theoretical overview of behavioural issues, aimed at giving a context for the consideration of low-level disruption. The discussion of the issues arising from the analysis of the transcript includes an argument for explicitly teaching aspects of classroom behaviour to children at the beginning of the secondary school years as a means of ensuring better access to classroom learning opportunities and greater autonomy for teachers to work with children in a proactive, rather than reactive, manner.