Resolução de problemas envolvendo área de paralelogramo : um estudo sob a ótica do contrato didático e das variáveis didáticas

Abstract

This research had the objective to investigate the possible relation between the concept of parallelogram area in a didactic book collection for the last grades of elementary school and the procedures used by students of an 8th grade class in the solutions to the problems related to this theme. The theoretical fundation is based on the model of area as magnitude, as it is in the works of Douady & Perrin-Glorian and Bellemain & Lima and in Theory of didactic situations developed by Brousseau and his disciple, particulary by the notions of didactic contract and didactic variables. The methodological procedures inspired by Bessot & Le Thi Hoai, consisted on the analysis of a collection of didactic Mathematics books, followed by the application of a test with students, users of the books. Twenty-one students of an 8th grade class of a federal public elementary school took part in this research in the city of Recife. The activities proposed were made in order to look alike on the books, but breaking with some rules of the didactic contract suppose standing the value of the didactic variables identified it was, in the time predominant in the didactic book collection, in the time value not used. The analysis of results indicated convergence and divergence among the abordage of the books and procedures by the students about the parallelogram area. For example, in the collection like in the procedures of the students, the side like base is generally the horizontal side (also when it´s not aborded the greatest side). The didactic book analyzed for beginning the measure of area only in a posterior moment worked the constancy of the area for decomposition and composition. This choice is against that one indicated in literature revision by the premature association of the surface to a number help the confusion between the magnitude length and area. Contrary to our expectation, on the activities proposed to great part of the students showed to discolour area and perimeter.