This study is based on an exploratory teaching experiment, integrating the use of GeoGebra, carried out with Brazilian pre-service mathematics teachers that were attending a Pre-Calculus course. We focus on the contributions of GeoGebra to the learning that the students evidence about the 'instantaneous rate of change', in this teaching experiment context. The results show that students benefited from the exploration of tasks using GeoGebra, evidencing significant learning in terms of the instantaneous rate of change, favoured by its multiple dynamic resources, which promote visualization, connections between different representations, and processes of mathematical reasoning associated with this concept. These elements constitute a model that shows the contributions of this software in the Calculus' learning process. In view of these results, the realization of exploratory tasks using GeoGebra is highlighted as a didactic proposal with potential for teaching Calculus in pre-service mathematics teachers courses, as this experience may encourage them and support their future teaching practices.