An Oral Proof in a Geometry Class: How Linguistic Tools Can Help Map the Content of a Proof

Recommendations that teachers promote argument and discourse in their mathematics classrooms anticipate researchers' needs for methods for examining and analyzing such talk. One form of discourse is oral arguments, including proofs. We ask: How can we track the development of an oral argument by a teacher and her/his students? We illustrate a method that combines Systemic Functional Linguistics (SFL) and Toulmin's argumentation scheme to examine how speakers logically connect different parts of an argument. We suggest that conjunction analysis can aid a researcher to map the content of a proof that has been constructed in class discussion. Using data from a discussion of a geometry proof, we show that different types of conjunctions enabled the teacher and the students to connect various components of an argument and, also, different arguments. The article illustrates how conjunction analysis can support and deepen what Toulmin's scheme for arguments can reveal about oral discussions.