3. Gravity for All

A: Gravity is very important.

B: What is gravity?

A: It's the force that pulls everything down.

B: I don't understand.

A: If you pour water into a glass, the water goes down into the glass.

B: Of course it does.

A: Without gravity, the water would go up.

B: You're joking.

A: Without gravity, you would go up.

B: What do you mean?

A: You would float into the sky like a balloon.

B: That would be fun!