# Posts tagged ball

## Icosahedron ball

Dec 28th

This icosahedron balloon is one of my favorites to make. Kids love playing with this balloon and tossing it around. I’ve posted a smaller version of this balloon before, but this is the large version (more than a foot in diameter.) It is made from six 260 balloons with a large round in the middle. (I like to use a polka-dotted balloon.) Each 260 balloon is used to create one basic unit, and after twisting six of them, you connect the six units with the balloon ends to form the icosahedron (20 faces.)

Check out this paper from Vi Hart, which contains instructions and pictures for making this balloon.

## Balloon ball (icosahedron)

Oct 1st

Here’s a balloon ball. Sure, you could just inflate a round balloon, but this is cooler. ðŸ™‚

In mathematical terms, it’s actually an icosahedron – a polyhedron with 20 triangular sides. It may look complicated, but because of its symmetry and basic units, it’s actually quite easy to put together. I first saw this on Vi Hart’s web site, where she has posted great instructions for this icosahedron, as well as many other mathematical shapes, such as fractals, tangles, and other polyhedra! Check it out!

**To make this balloon**, I took three 160 balloons and cut each in half. Each section was then used to make one of the six units. (I wanted to make an icosahedron that wasn’t too big.)

If you’d like to read a mathematical paper written about balloon twisting, check out: Computational Balloon Twisting Theory: The Theory of Twisting Polyhedra, co-authored by Hart, Martin Dermaine, and Erik Dermaine (who was one of my college professors!)

## It’s a balloon, it’s a toy, it’s modern art!

Apr 4th

This is basically made from two balloons twisted together, each containing a bouncy ball. I’d call it modern art, but give it to a child, and (after staring at it curiously) it becomes a toy! I got the idea of putting a ball inside a balloon from browsing balloonhq.com, which contains a tremendous amount of helpful information.

How do you get the ball into the balloon? In a future post, I’ll show you a little tool I made with a few items from around the house that you can use to put things into a balloon.