Abstract
Mathematical knowledge in classrooms is mediated through the use of both technical and
informal language. This paper is a report of a study of the language use of teachers as they
examine students’ work and discuss teaching for the topic of fraction operations. This
provides a window on their pedagogical content knowledge and also on the way in which
language is used to make sense of mathematical knowledge, either personally or for
students. It was found that some mathematical knowledge appeared to be taken as
understood, perhaps because the expected words were used.