Materials

• Balloon
• Water bottle

Instructions

• STEP 1: Pour the water out of the water bottle. Describe the water by its observable properties.
• STEP 2: Insert the balloon into the water bottle and pull the neck of the balloon over the outside of the bottle. Describe the air, inside the empty water bottle, by its observable properties.
• STEP 3: Place your mouth over the opening of the empty water bottle and attempt to inflate the balloon. Describe how attempting to inflate the balloon inside the water bottle can be used as a model to describe how matter is made of particles too small to be seen.

Explanation

The air inside the empty water bottle gets trapped when the balloon is placed over the outside of the bottle. When you attempt to inflate the balloon, the trapped air inside the bottle, prevents you from inflating the balloon.