Analyses were conducted of 110 lessons in 22 classrooms located in Melbourne, Hong Kong Shanghai, Berlin, Tokyo, Seoul, Singapore and San Diego. The focus of this paper is the opportunity provided in those classrooms for student mathematical talk and the consequences for student facility with mathematical discourse, as evidenced in 191 post-lesson student interviews. While student-student mathematical talk was a prioritised instructional tool in some classrooms, it was almost entirely absent in others. Some teachers demonstrably promoted student fluency with mathematical terms in public class discussion (e.g., Shanghai) and some did not (e.g., Seoul). In one of the Tokyo classrooms, student-student conversations were particularly rich with technical mathematical terms. In post-lesson interviews, students had the opportunity to use mathematical language to describe the lesson and what they had learned. Students from one of the San Diego classrooms made extensive use in interview not only of mathematical terms used during the lesson being discussed but of other mathematical terms never mentioned during the lesson; displaying both an extensive mathematical vocabulary and facility in its use. The results provide an opportunity to reflect on the prioritisation of student spoken mathematics, both as an instructional activity and as a desired learning outcome.