Classroom discussion plays an important role in developing students’ understanding of disciplinary concepts and discourse. It can also enhance their ability to express complex ideas and think critically (Aguilar, 2016). While students often present existing knowledge in discussions, they may create it too by negotiating meaning and by developing new, shared understandings through exploratory or academically productive talk (Mercer, 2004). This paper reports findings from a small-scale study of student discussions in one class on a 5-week pre-sessional programme. Small group discussions were recorded and analysed to determine the extent to which students’ talk appeared to be academically productive. Students also wrote brief reflections on changes in their speaking. Analysis of recordings showed that at first, discussions were cordial but uncritical, with few challenges to ideas and little explicit reasoning. Exploration of new meanings was limited. Later discussions appeared to be more exploratory as students demonstrated greater criticality, reciprocity and reasoning, to reach new understandings. Their reflections suggested a move from monologic or performance-based conceptions of talk to a growing understanding of talk as interactive, collaborative, and a means of learning. The main pedagogic implications are that academically productive talk appears to be more likely in open-ended tasks where students are encouraged to take divergent stances and engage with disciplinary content, supported by background reading.