Classroom discourse analysis on the identification of a triangle’s heights

Abstract

This paper focuses on the mathematical discourse of a classroom of 7^th-grade students, during a lesson concerning the identification of the heights of a triangle. The lesson took place after a sequence of activities during which the discourse on the mathematical object height has been constructed with students starting from its different possible realizations. The main goal of this study is to identify which of these realizations of the signifier height appear in the mathematical discourse of the classroom, to describe them, and to observe possible similarities or differences in relation to the most common realizations that the literature in Mathematics Education has reported on. The discourse analysis, combined with the construction and comparison of the expected realization tree and the students’ realization tree, allows us to highlight both the richness of the mathematical discourse of the participants and the interactions between different realizations. Finally, we discuss possible theoretical and didactical implications of the study.