- A beach ball is a kind of container
- If a flexible container is pushed on then that container will change shape
- A beach ball is flexible
- So, if a beach ball is pushed on, then the shape of the beach ball will change

- If a beach ball is pushed on, then the shape of the beach ball will change
- The beach ball is pushed on the middle
- Therefore, the shape of the beach ball will change

- Matter in the gas phase has variable shape
- Air is a kind of matter
- Air is in gas phase
- Therefore, air is a matter that has variable shape

- Air is a matter that has variable shape
- Matter with variable volume and shape takes the shape and size of its entire container
- Therefore, air takes the shape of its container

- Air takes the shape of its container
- A beach ball is a kind of container
- The beach ball is filled with air
- So, air takes the shape of the beach ball

- The shape of the beach ball will change
- Air takes the shape of the beach ball
- Therefore, the shape of the air in the beach ball will change with the shape of the beach ball

Therefore, the shape of the air in the beach ball will change with the shape of the beach ball
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?
Context: - Matter in the gas phase has variable shape 
- The beach ball is pushed on the middle 
- A beach ball is a kind of container 
- Matter with variable volume and shape takes the shape and size of its entire container 
- Air is a kind of matter 
- If a flexible container is pushed on then that container will change shape 
- The beach ball is filled with air 
- Air is in gas phase 
- A beach ball is flexible