Here’s a fun STEM building challenge for kids! Set up this bridge building activity and challenge kids to construct a sturdy LEGO® bridge that spans the width of the river. I love activities like this because they are beneficial and engaging for a wide range of ages.

In order to build a bridge, kids need to have a visual goal of the distance their bridge should span. I decided to use poster board as an easy way to create a river. I grabbed two sheets of poster board to use with 4 of my kids. If you’re doing this activity with a group, I would suggest one poster board for every 3-4 students. We easily fit all of our bridges onto one river, and the kids still had room to work.

You’ll want to have an assortment of bricks for this challenge. It really doesn’t matter what exact bricks they are as long as you have a good assortment of bricks and plates (flat bricks).

You may want to draw your river wider (or narrower) based on your kids. I was shooting for this activity to be an appropriate level for Janie (4) and Jonathan (6). For the older kids, I probably would have made the river a little wider to make it more challenging.

There’s all kinds of great vocabulary to discuss while building bridges. Kids can learn about the concept of a bridge’s span. You can also discuss what it means to reinforce something. The bridge’s beam, or the horizontal part of the bridge, needs to be strong and able to hold a lot of weight. Just one layer of LEGO® bricks won’t be very strong or hold much weight. If you reinforce your bridge with a layer of overlapping plates, it will be much stronger.

The supports of a bridge that go into the ground are called the piers or piles.

You can take the challenge a step further by testing how much weight the bridges will hold. The bridge on the left held an amazing amount of weight! Janie’s bridge (on the right) wouldn’t hold much weight, but she didn’t want to reinforce it at all so we didn’t. LOL. She was having too much fun lining up all her LEGO® girls on the bridge to care about the bridge’s functioning! Oh well, she’s only 4.

Besides being a fun STEM challenge, our bridges provided all kinds of entertainment!

Have fun building! Need more LEGO® STEM ideas?

Also, I have a LEGO® STEM book on the way! Genius LEGO Inventions with Bricks You Already Have is available for preorder now. Your copy will arrive on the release date – November 13, 2018. This book is packed with cool LEGO® inventions to build! 40 new projects with step-by-step instructions.

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  1. Sep 13, 2018

    It's a great idea! I wil try it with my son.

  2. summer Sep 22, 2020

    super fun

  3. KW Jan 5, 2021

    I love this and my kids loved it as well. The amount of problem solving is awesome. We tested various weights and due to the lovely sibling rivalry it made them want to go back and try to figure out a better way to make their bridge to make it stronger. Truly loved this idea. Super simple task to do but so much thinking involved. Sold me on the book.

  4. Tralena Hyslop Feb 23, 2021

    Great stuff, thank you, had a blast with the kids. Little budding engineer's. Love your artistic river art too, just a wonderful post to stumble upon. Thanks to your little engineers for demonstrating their amazing creativity.


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