Summary: A group of six balloons are tied together to form an octahedron. The balloons are popped one at a time to form the bipyrimidal and the tetrahedral shapes.
Six 9-12 inch balloons of different colors
Push pin in a cork stopper
Hints: Oddly, balloon phobias are common. You may want to warn your students that you’ll be popping the balloons. Also, the demo works better when the balloons are not over inflated.
Blow up the balloons to mid size and tie them together to form an octahedral shape. Pop the balloons to get the various shapes.