Crash Test Eggs

Today’s challenge was to build a car using K’Nex to save an egg passenger.


Design and build a car using only K’Nex with safety features that will protect an egg from breaking if it crashes into a solid object.

K'Nex Car


Egg –  boiled is less messy

K’Nex/LEGO/other construction materials

Elastic bands

Cotton Wool

Bubble Wrap

Test track area


Design a car to hold the egg so it doesn’t crack on impact with a solid object.

Think about how to protect the egg. 

  • Build a protective cage.
  • Add protective materials: bubble wrap, cotton wool etc
  • Try an air bag – balloon
  • Could you add some suspension?

Can you think of anything else? Would changing the type and size of wheel help?

K'Nex Car

K'Nex Car

My children came up with the design above which worked really well. The egg is set nicely back into the car so the front absorbs most of the impact, the egg is also held tightly in place, meaning it doesn’t move very much.

Extension Ideas

Try a different method of protecting the egg and design a test to investigate which method of protecting the eggs works the best.

Does your solution still work if you release the car down a ramp?

How can you make your comparisons a fair test?

crash test eggs

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