The air in the beach ball escaped. The air in the beach ball became a liquid. The type of air in the beach ball changed. The shape of the air in the beach ball changed.
I gave my students this multiple choice question: A student blew air into a beach ball and sealed it. She then pushed on the middle of the beach ball. What happened to the air inside the beach ball?

Only one answer is correct among these 4 choices:
- The air in the beach ball escaped.
- The air in the beach ball became a liquid.
- The type of air in the beach ball changed.
- The shape of the air in the beach ball changed.

Could you tell me which one is correct?

The shape of the air in the beach ball changed.