If You Built a Car…

what would it look like?  What kind of cool features would it have?  Jack, a young boy riding in the back of his dad’s car, comes up with the coolest car ever!  His car is made of a polymer gel to keep people safe, and it has a pool, a fish tank, and a snack bar!  In the book, If I Built a Car by Chris Van Dusen, we enjoyed being taken for a ride in a futuristic car that drives, floats, submerges, and flies!

After the story, students built balloon cars, and raced them with classmates.  It was a fun way to explore forces, and think like an engineer.

Focus: Engineering

Topic: Building a balloon-powered car

*Materials needed:

BookIf I Built a Car, by Chris Van Dusen

Half of a paper plate for each student

One whole straw, one straw cut to medium size (about 5 inches), and one small piece of straw (about 2-3 inches) for each student


2 pieces of spaghetti for each student

4 cardboard wheels, with holes poked in the middle (use a thumb tack)

4 marshmallows for each student

1 balloon for each student


Time needed: 30-45 minutes (45 minutes is much better, because then students can test the balloon cars, race them, and make adjustments if they don’t work right away.)

*Note:  I made a balloon-powered car of my own to bring with me and demonstrate.  I used the demonstration to engage students to have a conversation about forces.

Engage: Tell students that this story is about a young boy who invents an amazing car.  Ask if students have every wanted to build a car, or a house, or something in their bedroom that’s amazing.  Ask them to share some amazing, creative ideas.

Read the book to students, pausing to make predictions, share connections, and ideas. This book is written in rhyme, and is fun to read.  Students love that this car has a snack bar with squeeze cheese!  Cheese seems to make its way into many of my book choices, and many students have noticed that. Yum yum!


Explore: Ask students if they are ready to build a balloon-powered car that they can race and test with classmates.  Hand out supplies and take students through the steps to build their own.

Step 1:

Have students fold the half of the paper plate from a “smile” to “a piece of pizza.”

Step 2:

Have students attach the big straw and medium straw to the underside of the car with tape.


Step 3:

Have students put their two pieces of spaghetti through the straws, then put the wheels on, then finally the marshmallows to hold the wheels in place.

Step 4:

Hand out balloons.  I always tell the students to gently pull and stretch the balloons, because this will make it easier for them to blow the balloons up.

After students stretch the balloons, tell them to take the small piece of straw and put it halfway into the opening of the balloon.  They will fold the balloon around the straw, and then wrap tape around the balloon and straw together.  They will need to test the balloon to make sure no air is leaking around the tape.  If air is leaking, more tape will need to be added.

Balloon car building motor

Last step:

Time to attach the balloon to the car and start testing!  Have students tape the balloon motor on the car, with the “tailpipe” facing the rounded edge of the plate, so that the air goes out the back.Balloon car

Students had a blast testing and racing their cars:

Posted by Kim Angell, Children’s Assistant

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