Dialogic talk, in which different ideas are considered, promotes conceptual understanding in science, and is in line with South Africa's school curriculum. The problem is that dialogic talk is difficult to facilitate and may run counter to cultural norms. As a result, classroom talk is often not dialogic. This paper reports on the nature of classroom talk in the classrooms of eight physical science teachers who were prepared in their initial teacher education for a student-centred school curriculum. An observer spent two school days in each teacher's classroom, writing a narrative description of each lesson. A grounded analysis revealed two significant dimensions in the lessons: the nature of the talk and the apparent purpose of the teacher. The classroom talk could be classified as exposition, question and answer (Q&A) or conversation. The teaching purposes were: introduction of general principles, application, feedback and revision. The three types of talk were used to serve all four teaching purposes. Dialogic talk was present with all the teachers showing that dialogic talk is possible across the diversity of classrooms investigated. We consider factors that may inhibit dialogic talk, and ways to address these. We recommend that initial teacher education provides students with personal experience of dialogic talk in science classrooms, a framework for thinking about classroom talk and suitable pedagogies for facilitating dialogic talk.