This study aims to reveal features of student talk over a sequence of consecutive mathematics lessons in a large-size class in mainland China. By examining the time allocation for student talk and the number of Chinese characters spoken by the students, this study finds that, in some of the lessons observed, student talk added up to a longer duration and included a larger number of Chinese characters than teacher talk. But individual students were observed to have unequal opportunities to participate in public talk and there is a large gap regarding the number of Chinese characters that an individual student could speak in public. Each individual student's accountability to talk was recorded to be less diverse in public presentation than in non-presentation contexts (e.g., answering teacher questions). This study suggests that a unit of consecutive lessons can help a clearer and more comprehensive observation and analysis of student talk.