Activity time: 5 minutes
Materials for Activity
- Clear glass jar with metal lid
- A hammer and a nail, and modeling clay
- A large marshmallow and a plastic straw, for each participant who will try the experiment
- (Optional: Kitchen vacuum sealer may be used instead)
Preparation for Activity
- Using the hammer and nail, make a straw-sized hole in the center of the clear glass jar's metal lid.
- Place the straw through the hole in the lid and push it in about an inch. Use modeling clay to secure the straw where it passes through the lid; make sure you form an air-tight seal.
- Place a marshmallow in the jar and screw the lid tightly shut.
Description of Activity
Ask for a volunteer to draw all of the air out of the jar using the straw. Under normal conditions, molecules of air from the atmosphere (called atmospheric pressure) are pushing on the outside of the marshmallow. When the air that was once pushing on the outside of the marshmallow is removed, the air trapped inside the marshmallow pushes out (expands) causing it to get larger. The marshmallows shrink when the vacuum seal is broken and air rushes back into the container.
Then invite the participant to blow into the straw. As the air in the jar increases, the marshmallow will shrink.
If you have time, allow others to try the experiment. Use a new straw and a new marshmallow each time.
Process observations with questions such as:
- What happened to the marshmallow? Why?
- How does this experiment prove the existence of something (air) which cannot be seen?
- What does the experiment show us about seeking truth that may not be easily seen?
Including All Participants
If any participants are unable to see the experiment, have a co-leader or a participant verbally describe the activity as it happens.