Using Dynamical Geometry Softwares in the study of Plane Geometry: potentialities and limitations

Resumo

Background: Some inconsistencies that appeared when teaching Geometry - using Dynamical Geometry Softwares - to Mathematics undergraduate students, inspired this work . Objectives: To stress the potentialities and, specially, the limitations of Dynamical Geometry Softwares in order of using it correctly by teachers, pre-service teachers and students for learning and teaching situations and investigations in Geometry. Design: Critical analysis study of situations, with examples produced using Dynamical Geometry Softwares, in order to reveal some inconsistencies with respect to the theory. In particular, Geogebra was the software used. Setting and participants: Some of the examples presented here, elaborated in GeoGebra, were briefly discussed in classes of pre-service teachers of mathematics aiming at an awareness of the inconsistencies that may appear using a Dynamical Geometry Software. The authors are the unique participants of the elaboration of those examples. Data collection and analysis: There was not data collection, but only elaboration of examples in order to provide some arguments for future discussions. Results: Examples production shows some limitations of Dynamical Geometry Softwares and that those limitations are insurmountable due to epistemological reasons. Conclusions: Awareness of Dynamical Geometry Software limitations is fundamental for its correct use. Those limitations do not invalidate the software potential. On the contrary, being conscious of both potentialities and limitations of a hardware is a necessary condition to a fruitful use of it.