This study investigates teacher reformulation of student talk. The purpose of the study is to investigate the manner in which teachers affect the meaning and expression of students. The sociolinguistic design identifies reformulations in terms of linguistic form, semantic function, opportunity to confirm and the hard and soft quality of the reformulation process. An ethnomethodological method for establishing corroboration was adopted which allowed the teacher‐subjects the opportunity to review and evaluate the adequacy of the study's method of analysis and findings. The findings indicate that reformulation is a significant language device used by teachers to control classroom dialogue, teacher talk marks the official knowledge of classroom dialogue, and teachers disproportionately perform the language functions most commonly associated with higher‐order cognitive processing.