LEGO Balloon Powered Car STEM Activity for Kids
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Learn how to build a LEGO balloon powered car with this fun hands-on STEM activity for kids! This simple engineering project combines science, creativity, and play while teaching important physics concepts like air pressure, motion, force, and Newton’s Laws of Motion.
Inspired by the imaginative picture book If I Built a Car by Chris Van Dusen, this activity encourages kids to invent, design, build, and experiment with their own creative vehicle ideas.
This LEGO STEM challenge is perfect for:
- homeschool science
- classroom STEM lessons
- engineering challenges
- storybook STEM activities
- elementary science units
- rainy day building projects
Kids absolutely love watching their balloon powered LEGO car zoom across the floor using only air power!
Storybook STEM: If I Built a Car
One of my favorite ways to teach STEM concepts is by pairing hands-on activities with great books. If I Built a Car by Chris Van Dusen is such a fun read-aloud because it sparks imagination and creative engineering ideas right away.
The story follows a boy named Jack who imagines designing the ultimate dream car. His invention includes:
- a snack bar
- flying capabilities
- underwater driving
- robot controls
- pool and sports rooms
- autopilot systems
After reading the story, my kids immediately started brainstorming their own car inventions. It led perfectly into this LEGO balloon car engineering activity.
I even used this book during a homeschool co-op class, and the kids had so much fun designing and sketching their own creative vehicles before building the balloon powered cars.
Design Your Own Dream Car Activity
Before building the LEGO car, encourage kids to imagine and sketch their own invention.
Ask questions like:
- What would your dream car do?
- Would it fly?
- Travel underwater?
- Have robot helpers?
- Include a snack machine?
- Use solar power?
This simple extension turns the activity into a wonderful STEAM project by combining:
- engineering
- storytelling
- art
- creativity
- problem-solving
How to Make a LEGO Balloon Powered Car
Supplies Needed
- LEGO bricks
- LEGO wheels and axles
- Balloon
- Straw (optional)
- Tape (optional)
You can build your own custom LEGO car or modify an existing LEGO vehicle.
Watch the video below of me reading this book & my son teaching how to build the LEGO Balloon powered car.
Instructions for Building the Balloon Car
Step 1: Build the Base
Create a sturdy LEGO car with working wheels and axles.
Make sure:
- wheels spin freely
- the car rolls smoothly
- the base is balanced
Step 2: Build Balloon Supports
Create two small LEGO towers on top of the car to hold the balloon in place.
The supports should be tall enough so the balloon does not drag on the wheels.
Step 3: Inflate the Balloon
Blow up the balloon and twist the end slightly to keep air from escaping.
Place the balloon between the LEGO supports.
Step 4: Release and Watch!
Set the car on a smooth surface and release the balloon.
The escaping air pushes the car forward across the floor!
Kids love experimenting with:
- larger balloons
- different car sizes
- wheel designs
- added weight
- ramps and races
The Science Behind the Balloon Powered Car
This LEGO balloon car demonstrates several important STEM and physics concepts.
Newton’s Third Law of Motion
For every action, there is an equal and opposite reaction.
As air rushes out of the balloon backward, the car moves forward.
Air Pressure
The balloon stores compressed air inside. When released, the pressure forces air outward and creates thrust.
Potential and Kinetic Energy
When the balloon is inflated, it stores potential energy.
As the air escapes and the car moves, that stored energy changes into kinetic energy, or energy of motion.
Simple Machines
The wheels and axles on the LEGO car are examples of simple machines that help reduce friction and allow movement.
STEM Questions to Ask Kids
Encourage deeper thinking with questions like:
- What happens if you use a larger balloon?
- Which car design moves fastest?
- How does weight affect movement?
- What surface works best?
- What happens if the balloon points another direction?
- How can you improve the design?
This turns a simple activity into a true engineering challenge.
Turn It Into a STEM Challenge
Want to make this activity even more exciting?
Try:
- longest distance challenge
- fastest car race
- obstacle courses
- ramp testing
- redesign competitions
- themed vehicle inventions
Kids LOVE testing and improving their designs.
Car Snack Idea
We also made a fun edible car snack using:
- apple slices
- toothpicks
- grapes or olives
Simply attach grapes or olives as wheels using toothpicks.
This makes a fun STEM snack to pair with the activity and storybook.
Free STEM Lab Sheet
Turn this activity into a complete STEM lesson with:
- hypothesis pages
- observation prompts
- engineering design sections
- results tracking
- scientific method practice
Grab my free STEM Lab Sheet to extend the learning!
More LEGO STEM Activities for Kids
If your kids loved this LEGO balloon powered car, be sure to try:
It looks like you have a great time. Our boys love playing with lego and are great at making their own cars but we have never tried making a balloon propelled car. We will have to give it a go!
That book looks so cute!
We happened upon this book at the library, too and really enjoyed it! Glad to see you did this for Poppins Book Nook– great activities. I think my son would really like to try out a balloon powered lego car!
That is the coolest snack! My kids would love the book, the legos and the treat. Thank you for inspiring me!
Thank you for helping to bring a spoonful of reading fun to the Poppins Book Nook this month!
Oi,
amei os trabalhos de vocês.
Sou professora de robótica educacional e faço bastante experimentos com meus alunos.
Meus instagran espaço da robótica.
Parabéns.
We made some of these little cars, raced, then talked about the “secret” behind Mama’s vehicle performing sooo much better (aka science) 😛 After a period of independent redesign time, the small person’s racer came back lighter, more aerodynamic, and with a wide rear wheelbase. It really took off during our next race. What a way to teach STEM!
Love it! Glad you had a great time!