Relations between Area and Perimeter in Plane Geometry: the role of observables and regulations in the construction of explanation

Abstract

The teaching of plane geometry in elementary school is often lacking in meaning. Teachers choose teaching practices based on algorithms, without concern for the thinking processes involved in the construction of geometric thinking. This study is based on Genetic Epistemology to investigate how adolescents and adults who attended school, and were successful in learning geometry, construct explanations about problems involving the calculation of the area and the perimeter of plane figures. The data show that the interviewees are capable of doing the calculation with the algorithm, but very few show elaborated explanations. The explanatory models are the most varied, ranging from thinking based solely on perception to logical-mathematical explanations of the concepts involved. Keywords: Teaching of Geometry. Explanatory Models. Jean Piaget. Genetic Epistemology.