We describe and use an analytical framework to document mathematics discourse in instruction (MDI), and interpret differences in mathematics teaching. MDI is characterised by four interacting components in the teaching of a mathematics lesson: exemplification (occurring through a sequence of examples and related tasks), explanatory talk (talk that names and legitimates what comes to count as mathematics in a particular lesson), learner participation (interaction between teacher and learners and amongst learners) and the object of learning (the lesson goal). MDI is grounded empirically in mathematics teaching practices in South Africa, and theoretically in sociocultural theoretical resources. The MDI framework allows for nuanced descriptions of mathematics teaching and interpretations of differences in what is mathematically made available to learn.