Build exciting marble runs with 18 different pieces from the GraviTrax Starter Kit. Discover how the laws of physics influence the movement of the marbles on the track you design. The goal is to create a route on the marble run that allows the marbles to travel from the starting point to the finish line. Building a marble run is educational, as you learn how a marble reaches its destination along the track. There are unlimited possibilities for constructing a marble run, making it a very entertaining and educational activity for the whole family. You can expand the track and add challenges by purchasing additional accessories for the GraviTrax marble run separately. Challenge yourself, your friends, and your family to build a functional marble run.