In this paper, we report on an experimental activity for discussing the concepts of speed, instantaneous speed and acceleration, generally introduced in first year university courses of calculus or physics. Rather than developing the ideas of calculus and using them to explain these basic concepts for the study of motion, we led 82 first year university students through Galileo's experiments designed to investigate the motion of falling bodies, and his geometrical explanation of his results, via simple dynamic geometric applets designed with GeoGebra. Our goal was to enhance the students’ development of mathematical thinking. Through a scholarship of teaching and learning study design, we captured data from students before, during and after the activity. Findings suggest that the historical development presented to the students helped to show the growth and evolution of the ideas and made visible authentic ways of thinking mathematically. Importantly, the activity prompted students to question and rethink what they knew about speed and acceleration, and also to appreciate the novel concepts of instantaneous speed and acceleration at which Galileo arrived.

[url=http://dx.doi.org/10.1080/0020739X.2017.1377301] http://dx.doi.org/10.1080/0020739X.2017.1377301[/url]

This simulation allows you to manipulate the angle of inclination of the plane. [br]The point is to get familiar with the applet in preparation for the next activity.[br] [br]What shows you that it takes less time for the ball to roll down planes that are more steeply inclined?

After you have played for a while with the applet, please return to the learning materials and continue.