Materials

• Bicycle pump with rubber stopper
• 1-liter clear plastic bottle
• Bean-bag filler

Instructions

• STEP 1: Completely fill the bottle with bean-bag filler. Describe the filler by using its observable properties.
• STEP 2: Attach the pump to the stopper. Attach the stopper to the bottle.
• STEP 3: Pump the bicycle pump five times and observe. Remove the stopper and observe. Describe how the bottle can be used as a model to show how matter is made of particles too small to be seen.

Explanation

Pumping air into the bottle increases the air pressure inside, squashing the bean-bag filler. Once the rubber stopper is removed, the air rushes out, allowing the squashed filler to expand.