Experience the power of gravity! GraviTrax is the all new STEM track system from Ravensburger! Use your imagination to build superb tracks and set the gravity spheres rolling! Create the element of surprise! Use the Tunnels to hide the marbles as they travel through your track. Combine the Tunnels with your GraviTrax Starter-Set for added mystery to your track. Will you be able to keep your eye on the marble as it rolls through the tunnels? This STEM system [Science, Technology, Engineering and Math] is an ideal one to teach kids about gravity, magnetism, kinetic energy and fun. Hit a snag? Freestyle with your own track design or use the tasks and blueprints included to help you to get started in the world of GraviTrax! Are the gravity spheres stopping or flying off before reaching the end target? Time for some problem solving. Rebuild and try something different! The GraviTrax track system can be extended indefinitely with extra track packs and add-ons – each sold separately.