The Quality of Argumentation in an Euclidean Geometry Context: A Case Study

The research reported in this study examined the quality of argumentation of South African Grade 11 learners through the lens of Toulmin’s argument pattern (TAP). Very little research has quantified the argumentation of learners in mathematics across the school grades. The focus was on measuring the mathematical knowledge and quality of arguments formulated by learners as they engage in a reasoning task set in a Euclidean geometry investigative context. Mathematics education reform efforts have highlighted the importance of argumentation in the acquisition of mathematical knowledge. To describe these participants’ quality of arguments, a sample of 135 Grade 11 learners was drawn from a target population of high schools located in one large South African province. Using an analytical framework modified from Osborne et al. (2004), the findings suggested that although learners’ knowledge of properties of parallel lines was encouragingly satisfactory, the level of their argumentation quality was low. The implication of this finding is that mathematics initial teacher education programs need to design investigations that feature the TAP (core) in their courses. It is recommended that future studies may need to design intervention strategies to address high school learners’ lack of argumentation skills.