Informal formative assessment practices, which occur as part of the dialogic interactions happening in the everyday classroom, are not well understood by many teachers. The successful implementation of formative assessment practices is not widespread in school classrooms. This article examines one aspect of these dialogic interactions—namely, the use of teacher questioning—and argues that the potential exists for teachers to make use of the many formative assessment opportunities that occur in the regular classroom as part of the ongoing conversations between teachers and students. It draws on the ESRU (Elicits, Student, Recognises, Uses) questioning framework, and “assessment conversations”, to examine a sample of Year 9 mathematics classrooms in three New Zealand state secondary schools. It concludes that the ESRU framework has the potential to more fully describe the intent and outcome of questioning sequences in the mathematics classroom.