Mathematical discourse in the classroom has been conceptualised in several ways, from relatively general patterns such as initiation-response-evaluation (Cazden in "Classroom discourse: the language of teaching and learning," Heinemann, London, 1988; Mehan in "Learning lessons: social organization in the classroom." Cambridge, MA: Harvard University Press, 1979) to concepts for more fine-grained description such as the "Advancing Children's Mathematics" framework (Fraivillig et al. in "J Res Math Educ" 30(2):148, 1999). This article suggests a framework to be used for detailed studies of mathematical discourse on a turn-by-turn basis. This framework was used to study how single turns affect each other to form patterns in one teacher's practice. The method used belongs to conversation analysis: studying single turns and characterise these according to their role in the conversation. Two main repeating patterns were identified: one between student explanations and the teacher's focusing actions, and the other between the teacher's progressing actions and students' teacher-led responses. The findings also included other connections that demonstrate how various student interventions (explanations, teacher-led responses, unexplained answers, partial answers, and initiatives) are followed by different types of teacher actions. One implication is that, by developing concepts capable of describing qualities of a discourse on a turn-by-turn basis, it then becomes possible to analyse when mathematical talk fosters delivery of facts and when it fosters mathematical argumentation, debate, and critique.