Science Explorers
Science Explorers

Air pressure experiments for children are a fun way to introduce kids to a new scientific concept. Kids and adults alike have a blast with this balloon and jar air pressure experiment. The experiment shows children what happens when the air pressure inside a jar changes by using just a few materials. It’s the perfect lesson for elementary school-age children with adult supervision.

What You’ll Need

To perform the experiment, you’ll need:

  • Water balloon.
  • Glass jar.
  • Piece of paper.
  • Matches.

Safety Note

This experiment uses fire. Children must be supervised and should not perform the experiment on their own.

How to Conduct the Experiment

Follow these instructions to suck a water balloon into a jar using air pressure:

  1. Fill the balloon:  Fill the water balloon until it’s slightly wider than the neck of the jar and tie the balloon.
  2. Place the balloon on the jar:  Place the jar on a flat surface and rest the balloon on top of the open jar.
  3. Demonstrate with the water balloon:  Help the kids push down slightly on the balloon to show them it won’t fit inside the jar.
  4. Remove balloon:  After demonstrating, remove the balloon from the container.
  5. Get your matches:  Light a piece of paper with a match and drop it in the jar.
  6. Place the balloon again:  When the fire starts to grow, place the balloon back over the mouth of the jar.
  7. Watch the reactions:  Observe what happens to the balloon and the fire. The balloon will begin to shake, and the fire will be extinguished as the balloon is sucked into the jar. The balloon will be sucked about halfway into the container.
  8. Let the kids try:  Once the fire has died and the jar has cooled, have the children try to remove the balloon. It will be a little challenging!
  9. Safely remove the balloon:  To remove the water balloon from the jar, start by turning the jar sideways. Place your finger between the container and the balloon to release the suction. The balloon should come out easily after that.

Children will love doing this experiment over and over. To make this air pressure experiment even more fun for kids, let each child pick a balloon to decorate before you fill it with water. This allows children to observe any differences between how the balloons behave, such as which balloon was most difficult to remove and which one worked best.

The Science Behind the Experiment

This experiment is all about air pressure. When you first place the filled balloon atop the jar, air pressure prevents you from pushing it inside. The air trapped inside the jar has nowhere to go, since the balloon covers the opening. At this point, the air pressure within the jar is the same as the air pressure outside it, making it impossible to fit the balloon in.

But when you add the lit piece of paper to the jar, things change. The burning paper causes the air inside the jar to heat up and expand. As the fire grows, the air in the jar will start escaping around the sides of the balloon. When the balloon begins shaking that’s how you know the air is escaping.

The balloon acts as a one-way valve, allowing air within the jar to escape but preventing new air from entering. With less air in the jar, the air pressure drops. At this point, the air pressure within the jar is lower than outside it, which causes the balloon to get sucked in.

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