Here’s a fun LEGO building challenge and a great STEM activity for spring! Design cars that can transport an egg down a ramp. Challenge kids to build a car that will roll the farthest off the end of the ramp!

This is a great LEGO challenge to do at home, or with a STEM class or LEGO club. Kids can easily use whatever bricks they have, and it’s such open-ended fun.

I chose to hard boil our eggs before using them because I didn’t feel like cleaning up raw egg out of the LEGO bricks! However, you can use raw if you want and announce that keeping the egg intact is part of the challenge. It’s totally up to you!

You can see how we made our egg people here: Doodle Egg People. They’re so cute and fun!

LEGO Egg Car Design

When building a LEGO Egg Car, kids will want to make sure that there is adequate room for the egg to fit inside. They’ll also want to make sure that the egg is secure and won’t fall out during the trip down the ramp.

A car with more weight to it will have more momentum and will roll farther. Kids might think that a lighter car will travel farther, but that’s not the case! The heavier card will pick up more speed as it travels down the ramp.

However, you’ll also want to talk about friction. Thicker LEGO tires will have more friction with the ramp than the thin tires pictured above. Kids will also want to make sure that there are no bricks rubbing on the wheels as they turn.

On the car pictured above, my son had to adjust the wheels by pulling them closer to the outer edges of the axle pins. This kept the wheels from rubbing on the sides of the car and really increased the car’s performance.

Here’s a link to the thin wheels on Brick Link. Here’s the wheel, and then this is the tire.

The little gray pickup truck is cracking me up! My 9 year old built that one.

We used a nice smooth board as our ramp. This is something that we had leftover from our PVC Hot Wheels ramp.

Have the kids test their cars, and measure how far they travel past the end of the ramp.

Play with the cars just for fun, or add some math and science learning! You can try each car three or more times and then average the distances traveled. That’s a much more scientific way to compile the data than just trying the car one time. The might travel a little crooked on one run, for example. Averaging the distances gives you a more accurate overall measurement.

Try rolling the cars with the egg inside, and without. They should roll farther with the egg passenger because of the increased mass and momentum!

Have fun building and testing your LEGO egg cars!

Need more LEGO STEM ideas? LEGO bricks just really lend themselves so well to STEM learning. You can teach all kinds of physics concepts with fun LEGO building projects!

Here are 10 Must-Try LEGO Engineering Projects!


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  1. monica bishopp Mar 22, 2021

    My house of boys will be trying this! Thanks for the idea.

  2. Shelley Mar 22, 2021

    Our family can’t wait to try this! My son’s eyes grew twice their size looking at this one! Thanks for the ideas! We love them all!


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