Build a Bridge STEM Challenge


Kids love building. Give them any collection of materials and allow their imagination to run wild. It’s always exciting to see what they come up with. Encourage this creativity using simple, familiar materials. For this STEM activity, bring out the Lego! This Build a Bridge STEM Challenge can be set up in minutes and then your child’s imagination and problem solving skills do the rest!

This STEM challenge is part of 10 Exciting STEM Activities where you gather just ten simple materials and you’re then ready to do ten different, hands-on STEM challenges.

This build a bridge STEM challenge also includes a printable activity card so that you can give children the instructions/challenge and let them do the rest. You can also prepare bags, or kits, with all of the materials and the activity card to give children to work on the challenge at their own time, and pace. They make great educational gifts as well.

This bridge building challenge can be done inside or outside with just one or two materials. If you’re looking for more bridge building ideas, check out this popular collection of 10 Easy Bridge building STEM Challenges.

With this challenge, children of varying ages will attempt to create a bridge, using only Lego blocks, that reaches over a ‘lake’. Young children will work to create a bridge that is stable enough to reach across the water. Older children may create a more complicated bridge that includes some design elements or even raises and lowers.

build a bridge stem challenge shows a pinterest pin with plastic building blocks and bridges.

Benefits of STEM

STEM challenges are hands-on activities that encourage skills in Science, Technology, Engineering and/or Math. The more of these skills that are combined into the activity, the better.

STEM activities require problem solving, creativity, team work, critical thinking, trial and error and lots of imagination! For a huge collection of ideas for more STEM challenges, check out 45 STEM Challenge Ideas.

STEM challenges focus on the process. Not the end result. Remind children that they are not meant to create a bridge that is perfect in their first attempt. The challenge is intended to have kids try to create a bridge and then think about what worked well in each attempt, and what they can improve upon. Then in their next attempt, they keep all of the things that worked, and make changes to things that didn’t.

Build a Bridge STEM Challenge Materials

For this STEM challenge, you only need a few materials. You will need:

  • Plastic Building Blocks (Lego)
  • (Blue) Construction Paper
  • Activity Card (Optional)
build a bridge shows a blue wave made from construction paper, Lego and an activity card.

I have done this Build a Bridge STEM Challenge with children as young as three in preschool and older children in upper elementary. With STEM activities you can give the same challenge to children of different ages.

The complexity of the end result is where you will see a difference, but the challenge gives children of varying ages and abilities the opportunity to be successful.

To prepare your challenge, you can cut the construction paper to resemble a wave, or water or simply leave it in a rectangle. It’s up to you. If you don’t have construction paper you can use a piece of blue fabric, like a shirt or towel. Just about anything will work!

The challenge is to use the building blocks to build a bridge over the water (construction paper). The bridge must be able to stand on its own and the supports cannot be in the water.

bridge building shows an activity card that says use the materials to build a bridge over the water.

For a limited time, the Build a Bridge STEM Challenge activity card (shown above) can be downloaded for free, by subscribers. Information and how to subscribe is included at the bottom of this post.

Setting Up Your Build a Bridge STEM Challenge

There is virtually no prep required for this activity. Simply give each child doing the challenge a bunch of Lego and set out the piece of construction paper.

For younger groups, you can use a narrow sheet of paper and widen it for older builders.

The water is an important part of the challenge. It requires children to make a bridge that is a certain length. The bridge also has to be created in a way so that it balances across the water and is strong enough to stand on its own.

You can do the activity as a whole group activity by placing a long strip of paper across the floor. Each child has a spot around the water and access to Lego.

The more Lego that children have access to the longer and more complex their creations will likely become.

bridge building shows a child making a bridge from colorful lego.

Once the water is set out and Lego is given to children, they can start the challenge!

Bridge Building Challenge

Although the challenge is simple, creating the bridge is more challenging then it looks. In order to create a bridge that is wide enough to span across the water it has to have extra support through the middle to not tip or break.

Like most STEM challenges, there are more than more possible solution. You may be surprised by the ideas and creations your children come up with. I always love seeing solutions that I never considered.

stem challenge shows three bridges made from Lego.

Some of the bridges may have steps to get from one side to the other. Other bridges may be very simple and use a minimal number of pieces.

If children finish their bridge really quickly, you can encourage them to add details to make it look more like a real bridge or widen it so a toy car could fit and go across.

build a bridge stem challenge shows a bridge and printed activity card.

Many children will become really engaged and focused on creating their bridge and adding details and features to make their solution unique.

Other children may find it challenging to simply create their bridge so that it doesn’t fall down. Encourage them to keep trying different strategies to get their bridge to stand, but if they need help, suggest to make their bridge wider and with extra support across the middle and foundation (part that touch the ground).

In the end, have fun! Enjoy using an ordinary material, like Lego in a whole new way.

Bridge Building Extension Ideas

There are a few alternative ideas you can try with your Build a Bridge STEM Challenge. When I gave this challenge to an older child, they created a bridge that raises and lowers. This requires special Lego pieces, but if you give children a variety of pieces beyond just blocks, they may be able to get more creative.

build a bridge stem challenge shows a bridge that lifts and a purple lego boat going under it.

You can also challenge experienced builders to make a bridge that can open. Add the idea that a boat needs to be able to move across the water to the challenge.

You can also take the challenge outside. The pieces can easily be washed when the challenge is complete. Take the Lego outside and either create a small stream or bring the Lego for a hike and find a real stream to build across.

bridge building shows a child making a bridge in the sand with a stream flowing under it.

This Build a Bridge STEM Challenge is already a great screen free activity, but it is easy to also make it an outdoor activity where children can get some fresh air.

It’s up to you how you present this challenge to children. Do what works for you and your builders. However you make the challenge children will be learning, creating and having fun!

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