DIY STEAM Activity: Propellor-powered car!

Okay. There are lots of great kits for making DIY toy cars with kids – not to mention the balloon-powered speedboat activity in the back of the Built for Speed book that comes out in less than two weeks!

But sometimes, you need to improvise, because your kid wants to build something with motors and switches. I built this one with my 4-year-old in about an hour. I definitely “cheated” and it was not the most proper or elegant solution, but got the desired result. Here’s what I used:


  • Motor kit w/ assorted parts, wheels, propellors, etc. (There are many options if you want to source the parts separately or find a different bundle, but this is the one I used)
  • Stranded wire (like this)
  • Hot glue gun
  • Wire stripper (can use scissors instead)
  • Legos (4 cubes)
  • Batteries (AA or whatever works with your motor kit)

STEP 1. Set up the Circuit

The trickiest part of this is setting up the circuit. Especially when you have an impatient 4-year-old that you don’t want to solder with. That’s why stranded wire is nice. You can loop it around and twist it around itself for a quick and dirty connection. This is NOT recommended if you want this to last, but honestly, our circuit has been around for months and I just fix the connection when it gets loose.

Okay, I was also sloppy with my wire colors, but here’s how you want to connect them. Check to make sure your motor works by holding the red and black battery wires against each motor lead to see if it spins. Once you’re sure it’s working properly, attach the red battery wire only to the motor lead. Attach the black battery wire to a switch lead. Cut a piece of stranded wire and strip it on both ends (remove the casing without cutting the wire) and connect the remaining switch lead to the remaining motor lead.

As I built, I talked to my four-year-old about the circuit. I explained how for electricity to flow, there needs to be a complete loop. The switch breaks and re-connects that loop. So when the switch is on, the motor will spin. When the switch is off, the motor stops spinning.

Test it out and make sure the motor spins when you turn on the switch!

Step 2. Build the Chassis

Again, quick and dirty, I hot glued anything that didn’t need to move. So, first I hot glued the rails to the bottom of the main platform. I hot glued the battery pack on the top of the platform. I hot glued the switch and the lego tower on the top of the of the platform. I hot glued the motor onto the top of the lego tower.

Step 3. Assemble the Moving Parts

My 4-year-old added the wheels and the propellor to the chassis.

Step 4. Try it out!

Place the car on a smooth flat surface and turn on the switch! If the motor doesn’t spin, check your connections.

That’s it! My kid was so proud of this creation, learned about circuits and motors, and has kept it around for months – a definite parenting win! And if you haven’t already, don’t forget to order your copy of Built for Speed to inspire your kids in engineering, coding, and design!

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