Discourse has always been at the heart of teaching. In more recent years, the mathematics education community has also turned its attention towards understanding the role of discourse in mathematics teaching and learning. Using earlier classifications of discourse, in this paper, we looked at three types of classrooms: classrooms that engage in high discourse, low discourse and a hybrid of the two. We aimed to understand how the elements of each discourse affected classroom learning, relationships between teachers and students, and participatory structures for students. Overall, our findings highlight the important relationship between cognitively demanding tasks and mathematical talk, and the power of discourse as a ''thinking device'' as opposed to mere conduit of knowledge. Our work also points to the under-theorized nature of hybrid discourse in mathematics classrooms, thereby providing some directions for pedagogy and further research. (Contains 4 tables and 4 figures.)