Designing GeoGebra Tasks for Visualization and Reasoning

Presentation in GeoGebra Global Gathering 2015 Or, A.C.M. (2013). Designing tasks to foster operation apprehension for visualization and reasoning in dynamic geometry environment. In C. Margolinas (Ed.) Task Design in Mathematics Education: Proceedings of ICMI Study 22, pp. 89-98, Oxford, U.K. https://hal.archives-ouvertes.fr/hal-00834054v3.
Designing GeoGebra Tasks for Visualization and Reasoning