We recently celebrated my son’s birthday! He likes doing our STEAM activities so I wanted to think of a birthday themed experiment for us to do together. We had extra balloons from his birthday decorations, so I knew I wanted to use balloons in our experiment. Our recent experiment The Fire and The Flood was a big hit with my kids, so I decided to use that same air pressure concept but in a different way.

This activity uses both balloons and fire – two things seen at most birthday celebrations. We originally wanted to use a candle in this experiment but we were unsuccessful with the candle, so we pivoted and used paper instead.

If you enjoy experimenting, I recommend you try it with both a candle and paper like we did. I think if your mason jar is smaller than ours a candle might work, but in our case the small birthday candle just didn’t put off enough heat to make this experiment work for us.

My kids and I had lots of laughs while doing this experiment – as you can see in our YouTube video!

You don’t have to be celebrating a birthday to try this activity. This is a fun experiment anytime of year! But if you’ve had a recent birthday like us, you can sing like I did in the YouTube video while lighting the candle. 😉

Check out the video of our experiment below then read on for all the step by step details.

Safety:

This experiment involves fire. Adults should light the paper on fire and handle the jar once it heats up. Please keep children a safe distance away from the flame to prevent burns. I’d recommend this activity for kids ages 4+ (kids who can follow directions well and understand that fire will burn).

Materials: 

  • Mason jar
  • Paper
  • Lighter
  • Balloons
  • Water

Procedure:

  1. Fill a balloon with water – just full enough to be slightly larger than the opening of the mason jar.
You can see our balloons are slightly larger than the jar opening. I would recommend making the balloon even a little smaller than ours.
  1. Crumple a piece of paper (about 1/4 of a letter size piece of paper) and place it inside the mason jar.
  1. Adult: Carefully light the paper with a lighter.
  1. Once a good flame is burning, place the water balloon over the top of the mason jar.
  1. Observe what happens: the water balloon will be pushed partially into the jar once the flame burns out.
  1. Try to remove the water balloon: you’ll be surprised that it’s very difficult to pull the balloon out of the jar!
  1. Repeat steps 1-6 using a balloon filled with air instead of water. Are your results any different?
Our balloon filled with air was not pushed as deep into the jar as our balloon filled with water.

STEAM Concepts Learned:

Fire needs oxygen, fuel, and heat to ignite and continue burning. The paper is our fuel, the air provides the oxygen, and our lighter was the heat to start the flame. Covering the opening to the mason jar with the balloon cuts off the source of oxygen for the fire. But the flame didn’t go out immediately because there is oxygen trapped inside the jar. Eventually all the oxygen in the jar is consumed by the fire and the flame dies out.

Once the flame dies out, the air inside the jar cools down, which decreases the air pressure inside the jar. The air outside the jar is at higher pressure and wants to equalize with the lower pressure air in the jar but the balloon is trapped between the two air pressures. The outside air pushes balloon inside the jar until there is an equilibrium of pressure inside and outside the jar.

As soon as the flame burned out our balloon is pushed into the jar

My kids were surprised and amazed watching the balloons get pushed inside the jar. They were equally surprised by how difficult it was to remove the balloon!

We had a blast with this experiment. Even if you’re not celebrating a birthday, we hope you’ll try this easy to set up and execute experiment – you won’t be disappointed! It’s a perfect activity for a long holiday weekend at home.

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