How about making a car that runs on air! Introduce your child to the power of jet propulsion and thrust with Smartivity Super Duper Propulsion Car S.T.E.M. Educational D.I.Y. Toy Kit. A redesign of our most popular activity project in the 6+ age-group, the Super Duper Propulsion car now comes with extendible tracks and additional learnings about friction and gradients. Once assembled, children can lay out the tracks they have build and change the length of the track as they please. The tracks have a flat element and an adjustable gradient/slope element. Using the breakers on the flat tracks, children learn the concept of friction and braking. While by changing the notches of the adjustable gradient children understand the variation in power required to climb an incline. This exploratory and playful learning activity is bound to keep your child engaged for a long time.