The Hoberman Sphere combines mathematics, geometry and aesthetics into a magical motion of surprising simplicity, beauty and fun. This glow in the dark sphere magically transforms from 9.5 inches to 30 inches. Toss it around the dark and watch the glowing fireflies dance, or suspend it from your ceiling and let the fireflies send you off to sleep! A game and activity sheet is included. Everyone who sees these spheres is fascinated. You can use this for physics or astronomy to demonstrate the idea of an expanding universe, for mathematics to show the volume, surface area and diameter relationships of a sphere or for chemistry to model Charles and Gay Lussac's Gas Laws as applied to a soap bubble. Great for a party. Its system of polymer links expands and contracts almost effortlessly, changing in volume 30 times. Hang it from the ceiling and using the pulley, create an expanding mobile you can open and close. No assembly required - you will not want to put it down. Ages 4 and up.

• Glow in the dark
• Expands from 9.5" to 30"
• Ages 4 and up
• 21 cool things to do