LEGO Zip Line Activity: A Fun STEM Challenge for Kids

You can learn so much from a simple LEGO zip line activity! Let your child design his own “cage” that will send the minifigure down the zip line!


My kids went zip lining for the first time in France last summer, and they absolutely loved it. I was having mini heart attacks watching my 3 and 5 years old flying through the air, but they had a blast.

So when I mentioned that we are going to try and build a LEGO zip line, they were on it!

What is awesome about the LEGO zip line activity is that there is no one way to design the zip line “cage, or the structure that holds your LEGO minifigure. After playing with the zip line for an hour and a half, I lost track of how many designs we created.

How to Make the LEGO Zip Line



  1. Build your cage – this should be a structure that can hold the LEGO minifigure with a hole on the top where the zip line will go through.
  2. Put the LEGO minifigure in the cage.
  3. Tie one end of the string to a doorknob, back of a chair, or any place that is stationary and higher up. 
  4. Thread the string through the hole.
  5. Pull the string so that it’s taut and hold the loose end tightly and on a decline. 
  6. Push the cage all the way to the highest point of the string.
  7. Let go of the cage watch it slide down the zip line!

Science Behind the LEGO Zip Line

While the LEGO zip line may seem like just a simple, fun activity, there are so many science concepts that you can teach your kid. As your child experiment with different designs, talk about:

Gravity: Why do the minifigure and the cage go downward on the zip line instead of sliding upward? Gravity is the force that pulls objects toward the center of the Earth. In this case, gravity is pulling the LEGO pieces to the ground.

Friction: Why do some cages slide down smoother than others? Friction occurs when one object rubs against another. Friction works against and acts in the opposite direction of motion.

Slope: How can you make the same cage design slide down the zip line faster or slower? The slope describes how steep a straight line is, and you can change the slope of the zip line by moving the end of the string that’s touching the ground.

Speed: How fast does the cage move down the zip line? Speed is the measure of how fast something is moving or the distance that an object moves in a certain amount of time.

Weight: Do heavier cages slide down the zip line faster? Weight is the force gravity applies to an object and has an impact on speed.

We love this simple LEGO activity because we can experiment with so many variables. 


Here are some of the things we tried:

  • Make the zip line steeper. Did the cage go faster or slower?
  • Do the opposite and make the zip line longer and hold it at a gradual slope. Did the cage go faster or slower?
  • Add on a few more LEGO blocks to the bottom of the cage to make it heavier. How did the increased weight affect the speed at which the cage slid down the zip line?
  • Design a cage that is very wide. How did that affect the cage when it traveled down the zip line?
  • Use a round piece of LEGO instead of a flat piece for the hole. Did the cage slide down smoother?
  • Change the tension by making the string more or less taut. How does that affect the cage?

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One thing we didn’t get to try is using a wheel on the string. We just didn’t have one big enough. If you do, I suggest making a pulley and try to see if the wheel makes your LEGO guy go faster down the zip line.

Before each experiment, ask your child what he or she thinks is going to happen. For example, after you make the slope steeper, ask your child if he or she thinks the LEGO cage is going to go faster or slower. This is so great for their critical thinking!


Final Thoughts on the LEGO Zip Line Activity

Building a zip line with LEGO bricks is one STEM activity your kids will love. We learned so much through this activity and my son built so many different cage designs. I really hope you try it out! 

What’s wonderful is that even though my 3 years old was too young to build a good cage, she was able to participate by holding the zip line or sliding the cage down the string. 

STEM fun for the whole family! 

YOU MAY ALSO LIKE: Penny LEGO Boat Challenge

Want this activity in an easy-to-print file? I have compiled 5 super fun LEGO STEM activities for kids in a printable PDF.

Each activity includes a list of supplies, step-by-step directions, an explanation of the science behind the activity, and different extensions based on the science concepts.

The ebook includes:

  • Balloon-Powered LEGO Cars
  • LEGO Zip Line
  • Penny LEGO Boat Challenge
  • LEGO Volcano
  • LEGO Plinko Board


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