Geometric constructions in a dynamic environment (GeoGebra): The case of in-service teachers

Dorit Cohen (1) , Anatoli Kouropatov , Regina Ovodenko , Maureen Hoch (2) , Sara Hershkovitz (3)

1 Bar-Ilan University [Israël]
2 Center for Educational Technology
3 Shaanan College

A unit on dynamic geometric construction was included in a professional development course for in-service mathematics teachers. As a final task in that unit 28 teachers were required to construct a rhombus based on their own choice of given objects and tools, using the dynamic geometry software GeoGebra. Their responses were analysed according to: the choice of given objects; the choice of tools; the explanation and validity test; and the number of different rhombuses they claimed to have obtained. The teachers were found to have different concept images of a rhombus and different conceptions of what constitutes a valid geometric construction. While many claimed to have obtained an infinite number of different rhombuses, differences were observed in the "type of infinite". Recommendations are given for improving the task design to strengthen teachers' mathematical and pedagogical knowledge.

Mots clés: Geometric construction; dynamic geometry; GeoGebra; concept image; in-service teachers

Domaines: Mathématiques [math]; Sciences de l'Homme et Société

Dorit Cohen, Anatoli Kouropatov, Regina Ovodenko, Maureen Hoch, Sara Hershkovitz. Geometric constructions in a dynamic environment (GeoGebra): The case of in-service teachers. CERME 10, Feb 2017, Dublin, Ireland. ⟨hal-01925525⟩