Build and Race a Balloon Car!

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Does your kid love toys that go fast or racing of any kind? Then today’s experiment is a good one to combine that love with some engineering!

Building and racing a homemade balloon car is a great way to teach engineering and problem-solving to your child. There are lots of variables involved and, if any go wrong, your child will have to figure out the problem to make the car race again.

It’s a fun and engaging engineering experiment with a fun ending (racing!).

build a balloon car engineering experiment for kids and preschoolers

How to make the Build and Race a Balloon Car engineering experiment

Supplies you will need

For this experiment, you will need the following:

Before you start

We are using a small screwdriver or a hammer and nail to cut a small hole in our bottlecaps, so please watch your child while performing that step.


Here is how to do this experiment with your toddler:

Step 1: Make the base of the car

First, we’re going to make the base of our car that everything will attach to.

Cut your piece of cardboard into a rectangle that is about 4-5 inches long and about 2-3 inches wide.

Step 2: Add the axles and wheels

Cut one of your straws to the width of the cardboard and repeat once more. Tape these two straws onto the base of your cardboard, making sure not to make them too close to one another (far enough away that the bottle caps will not touch). Think about where axles are located on a car and tape them in that area.

Next, take the two wooden skewers and cut them to have a couple of inches of clearance on either side of the straws. My skewers were about 12″ long, so I was able to get away with using just one skewer and cutting it down.

Insert one skewer per straw.

Get your preschooler involved: Inserting the wooden skewers is a great fine motor skill for your child!

Step 3: Puncture a hole in each wheel and place on the axles

In this step, we are working with sharp materials, so please watch your child.

Using a small screwdriver or a hammer and a nail, you will puncture a hole in each of your four bottlecaps, near the center of each cap. They have to fit onto the skewers, and if they end up too big, you can add some glue around the hole to keep it in place.

Once each cap has a hole in it, go ahead and place a cap on each axle end.

Step 4 (optional): Decorate your car

Decorate your balloon car with markers or stickers to make it unique and fun!

Get your preschooler involved: This step is all about your kiddo decorating their car with stickers, markers, crayons, pens, or whatever they want!

Step 5: Add the propulsion

Use tape to attach the end of the balloon to the straw nozzle. Make sure that no air can escape! Inflate your balloon by blowing into the straw.

Using tape, attach a straw to the top of the cardboard base, towards the back. This will serve as the nozzle for your balloon car.

Find a smooth surface to race your balloon car on, like a hardwood floor or a table. Place your car at the starting line and let it go!

Step 6: Experiment

Once your car is built, you can race! But isn’t it a little more fun to test out ways to make it faster and go farther?

You can try experimenting with different sizes of balloons, different lengths of straws, and different weights for the cardboard base to see how it affects the speed and distance.

Another test is adding some weight to your car to see how it affects its performance. You can do this by attaching small objects like coins or paper clips to the cardboard base.

Finally, try racing your balloon car on different surfaces like carpet, grass, or tile. How does the surface affect the movement of your car? Does it move faster or slower on different surfaces?

The engineering behind the Build and Race a Balloon Car engineering experiment

This experiment teaches:

  • Introduction to Engineering and Design
  • Understanding Basic Physics Principles
  • Importance of Variables and Testing

How it works

The balloon car experiment works by utilizing the force of air pressure to propel a car forward. When the inflated balloon is released, the air rushes out through the straw, creating a backward thrust. As a reaction to this force, the car moves forward.

The wheels (bottle caps) reduce friction between the car and the surface, allowing it to roll smoothly.

By adjusting variables like balloon size, weight, and surface, we can observe how these factors affect the car’s speed and distance traveled, providing an introduction to the basic principles of physics and engineering.

Introduction to Engineering and Design

Building and racing a balloon car gives us the opportunity to introduce the concept of engineering and design.

Through this experiment, we can teach how to piece together the right materials and components to create a vehicle. And not just any vehicle; a vehicle that moves!

This experiment allows them to engage in problem-solving, critical thinking, and hands-on construction, fostering their creativity and spatial awareness.

Understanding Basic Physics Principles

The balloon car experiment provides a simplified introduction to basic physics principles.

We can observe how the air escaping from the balloon propels the car forward. If you want to get super specific with your child, you could even talk about Newton’s Third Law of Motion (every action has an equal and opposite reaction).

They can also learn about friction by experimenting with different surfaces (carpet versus tile) and observing how it affects the movement of the car. You could also test out your car on an uphill and downhill to see how it changes the speed of your car!

Importance of Variables and Testing

This experiment encourages preschoolers to explore and understand the concept of variables when conducting a STEM experiment.

What are some variables in this experiment?

We can experiment with different variables such as balloon size, weight distribution, and surface types to observe how they impact the performance of the balloon car.

This experiment is a great opportunity to teach the importance of testing and making adjustments to get better results. It’s also a good one to practice problem-solving to get your balloon car going the farthest and fastest it can go.

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