Space hopper
Overview
 
A space hopper, also known as a moon hopper, skippyball, kangaroo ball, bouncer, hoppity hop, or hop ball, is a rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...

 ball (similar to an exercise ball) with handles which allow one to sit on it without falling off. The goal is to hop around with it, using the elastic
Elastomer
An elastomer is a polymer with the property of viscoelasticity , generally having notably low Young's modulus and high yield strain compared with other materials. The term, which is derived from elastic polymer, is often used interchangeably with the term rubber, although the latter is preferred...

 properties of the ball to move forward.

The term "space hopper" is more common in the UK; the toy is less familiar in the United States, and may be known as a "hoppity hop" or some other name.
 
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