Air pressure experiment with water bottle and balloon explanation

Use heat to change the air pressure inside a bottle causing a water balloon to squeeze into a bottle with this water balloon in a bottle low-prep STEM experiment!

The egg or balloon in a bottle experiment is a total classic and one we could definitely not exclude from our low-prep STEAM activities! It takes just a few minutes to do and sets the stage for a lot of great questions and exploration!

I have to admit, I had a bit of trouble keeping my paper lit, but after some tenacity and discussion about changing my method we managed to get it to work a few times for us and it was totally worth it!

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Why STEAM Activities?

STEAM is the abbreviation for Science, Technology, Engineering, Art, and Math.

STEAM, like STEM, is an integrated approach to learning that encourages learners to make connections between the concepts they are learning and how they apply them to real-world problems.

STEAM helps students ask questions, problem solve, think creatively, and produce innovative solutions. Many schools have adopted STEAM learning activities into their curriculum, but it’s never too early to start building critical thinking skills.

We love to learn through play at our house and have a blast doing activities for toddlers all the way to tweens!

Under Pressure! Water Balloon in a Bottle Activity Materials

• Large glass bottle (We used a Pyrex bottle because it is designed for high heat applications, which is important for this task!)
• Balloon
• Water
• Paper/Coffee Filters/Birthday Candle
• Lighter/Matches

CAUTION: Please make sure to take appropriate safety precautions while doing this experiment and only conduct this experiment under adult supervision.

Fill your balloon with water so that it is slightly larger than the mouth of your glass and tie a knot. Make sure the outside of your balloon is slightly wet.

If your balloon is too big then it will go into the bottle and stop. This happened to us…a bunch!

Use a lighter or match to light a small piece of paper. Let it burn for a second before dropping it into your bottle. Ultimately, a coffee filter was the most effective way for us to keep a flame going in our bottle.

Place your balloon on top of the bottle. Make sure your knot is not in the way. It takes about 30 seconds for the balloon to get sucked into the bottle. If it gets stuck, you might have too much water. You can try again with a smaller balloon.

The Science Behind the Water Balloon inside a Bottle Activity

Just like the classic egg in the bottle experiment, this experiment demonstrates how air pressure can be used to push a water balloon into a bottle. As the air inside of your bottle is heated by the burning paper, it expands.

The expanding air pushes up and escapes out the top of your bottle. You might notice your balloon bouncing a little bit while this is happening. Once your flame uses up all of the oxygen inside the bottle, it dies out.

The air inside of your bottle begins to cool and contract. Since your balloon is blocking the top of the bottle, air cannot enter the bottle, which forms a partial vacuum inside of the bottle. As the pressure inside of the bottle drops, the higher pressure outside of the bottle forces your water balloon into the bottle.

How to Get the Water Balloon Out of the Bottle

Because the water balloon is not firm, it is not possible to blow air into the bottle to get the balloon out. You also can’t pull the balloon out because it creates a perfect seal. Trying to pull the water balloon out might burst the balloon.

To remove the balloon, you’ll need to use a straw or similar object to equalize the air pressure, which will make it much easier to remove the balloon from the bottle.

Want to connect this Balloon in a Bottle Activity with other STEAM buckets?

Check out these STEAM extensions!

Science

Try the classic egg in a bottle experiment with a hard boiled egg! Compare the similarities and differences between using a water balloon and a hard-boiled egg.

Technology

Make a stop motion video of your demonstration! Share with friends!

Engineering

Make a Balloon Car!

Art

Use your balloons to do some balloon painting!

Math

Weigh your water balloon and your bottle before your experiment. Then weigh them after the balloon is in the bottle. What do you notice?

Some Books to Read with Your Air Pressure Science Activity

We love incorporating books into our activities. Here are some great books about science to read with your activity!

• Ada Twist, Scientist by Andrea Beaty
• Say Zoop! by Herve Tullet
• The Most Magnificent Thing by Ashley Spires

31 Days of Low-Prep STEAM Activities for Kids

This activity is part of our 31 Days of Low-Prep STEAM Activities for Kids. Every activity will primarily focus on each of the buckets of STEAM (Science, Technology, Engineering, Art, & Math) although these integrated projects fit in more than one bucket.

You and your kiddos are going to love all of the activities that we have in store! Visit the 31 Days of Low-Prep STEAM Activity hub and pin it, so you can come back and visit it daily!

PIN THIS IMAGE TO SHARE THIS LOW-PREP STEAM ACTIVITY!

Meet Toni, the Maker Mom behind Our Family Code

Hey there, I’m Toni! I’m a software engineer and Maker Mom that finds my joy in unleashing my children’s curiosity by exploring STEAM concepts with my fantastic five!

When I’m not chasing toddlers or raising tweens, you can find me tearing things up and putting them back together over here at Our Family Code.

I am the owner and content creator of multiple educational websites designed to increase access to STEAM & STEM education with a focus on teaching computer science and coding to kids of all ages!

You can also find out more about me by visiting ToniGardner.com!