Types and shapes

Just like the outside of a balloon is a round surface, the outside of a ping-pong ball is also a round surface. But the surfaces formed by soap bubbles are much more interesting. They can stick together to form complicated shapes and are also wobbly and a little springy.

You can see how springy surfaces can be by thinking about how a soccer ball bounces. The soccer ball is much stronger than a soap bubble which pops easily if you touch it.