OKAY, BUT WHO IS THALES? ACTIONS FOR STUDYNG AND LEARNING CONCEPTS CONCERNING SIMILARITY OF TRIANGLES

Abstract

The article addresses the issue of learning concepts related to geometry and proposes to solve the question: what study actions developed by students indicate mathematical learning about the similarity of triangles? Related to this question, the aim is to analyze the study actions developed by students in the ninth year of elementary school when solving tasks on the similarity of triangles. A formative didactic experiment was carried out with twelve ninth-grade students from an educational institution in the city of Goiânia-Brazil. The data produced involves the students’ written records of solving tasks, which are analyzed based on Cultural-Historical Theory. The results show actions related to the study of the historical development of the concept of similarity, demonstrations of metric relations in the right triangle and the resolution of exercises that signaled the students’ engagement in mobilizing their learning processes.