Lego Displacement Experiment for Kids

Welcome back for another STEM Saturday! We have been working on something super fun and super secret that I can’t quite tell you about. However, I can tell you that it has something to do with this awesome Lego Displacement Experiment for Kids. You know how much we love simple science for kids. If you kids love Lego, they will love this!

Displacement with Lego Simple Science

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We have been doing a lot of Lego activities lately. We’ve made lego marble mazes, Lego memory games, and even done some fun math with Lego. We couldn’t stop there and not add in some awesome simple science with Lego.

Lego Displacement Experiment for Kids

Lego Displacement Experiment Supplies

Setting up the Lego Displacement Experiment for Kids


2 Measured Containers of Water (we love these beakers)
Lego (we uses 2×2 and 3×2)

Measuring Cups

Set Up:

This experiment is super simple to set up. Simply fill two glasses with water at the same level. Place your pile of Lego next to the glass and invite your children to participate.

Conducting the Experiment

Before you begin, chat with your kids about the level of the water. You can show them examples of displacement using ice cubes and water, or you can let them discover it on their own. Talk about what they predict will happen when they put the Lego in the glass and how many Lego they think they will need to change the level of the water.

lego Discplacement Experiment Steps

As you drop the Lego in one at a time, keep track of the total (we love to tally ours up to practice a little more math).

Displacement Experiment with Lego

The challenge is to change the water level without adding any more water to the container.

Lego Displacement Experiment with Water

When you use an item such as Lego that float, noticing the change in the water level can be a little difficult. If your children are very young, I would suggest using items that sink (we found out that Lego wheels work perfect).

Displacement Experiment with Lego Full Glass

Done. 30 2×2 Lego finally made our water level rise to 200ml from 150 ml. But would that always be the case? Does it matter the size of the Lego brick?

Lego Displacement Experiment with Kids

Now, comes the fun part. Try different Lego in the other container and compare the changes.

Making Observations and Noticing

We immediately noticed that it took less 2×3 bricks to displace the water the same amount. If you have an older child or want to challenge their math, they might love this next part.

My boys noticed that it took 30 2×2 bricks and 20 3×2 bricks. When they did the math, they realized that this was the same “area” of Lego bricks. They were floored. What do you think your children would find?

Lego Displacement


Do you have a favorite Lego Science Experiment? I would love to know! Connect with me on Facebook, Twitter, Google+, Pinterest, Instagram or subscribe by email. I can’t wait to hear your ideas.

Science Books for Kids

Awesome Books of Science | The Curious Kids’ Science Book | Tinkerlab | Kitchen Science Lab | Candy Science Experiments


STEM Activities for kids

Still wanting more STEM activity ideas? Luckily you can always head over to last week’s post and check out more great resources!


Sand Castle STEM Challenge from Preschool Powol Packets
Wind Power LEGO Car Races from Handmade Kids Art
February Science Calendar from The Homeschool Scientist
Fishing for LEGO Ice Minifigures from The Science Kiddo
Free Printable Human Heart Fact Valentines from Suzy Homeschooler

For More Adventures in Learning

Lego Calm Down Jar with lego

lego Excavation Simple Science


Discover how to get siblings to get along even when all they do is annoy each other with the Sibling “Get Along” Poster Pack!

5 thoughts on “Lego Displacement Experiment for Kids”

  1. Pingback: STEM Saturday: Free Printable Human Heart Fact Valentines | Suzy Homeschooler

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  4. Pingback: LEGO Summer Bucket List Challenges - Lemon Lime Adventures

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