This article reports on what happened when a mathematics teacher at an urban, New Zealand secondary school trialled the use of oral and written language tasks with his Year 9 mathematics students (two classes) as a way of developing their understanding of algebra. Over a period of five weeks, he trialled the use of a range of activities that were new to his practice and were designed to encourage students to use oral and written language to express their algebraic understanding. A range of data was collected in relation to this "intervention"--pre- and post-intervention questionnaires, test results and teacher observations. Findings suggested that the activities collectively contributed to a marked increase in students' algebraic confidence and willingness to use algebraic discourse in expressing and reflecting on their learning. It is argued that these findings have implications for mathematics instruction and, more generally, for disciplinary literacy theory.