Family STEAM Challenge: Engineering LEGO Bridges

Ask your kids

Next time you are driving across a bridge with your kids, ask them, “What do you think is holding us up? Are we floating in mid air? How do you think our car is being held off of the ground?”

You can then explain that bridges aren’t magic, but that they transfer our weight from where we are down to the ground in a different spot, or distributes it to the ground over several different spots.

Different Types of Bridges

You can tell your kids that the engineering behind bridges uses pushing and pulling forces to transfer the weight of the load. Below is a picture showing the six major types of bridges used today, including beam, arch, truss, suspension, cantilever, and cable-stayed.

How These Bridges Work

Looking at the above designs can you see, how, if your car was in the middle, the bridges would use pushing and pulling to forces to transfer your weight?

For example: With a suspension bridge, if your car was in the middle, it would pull on the vertical cables which would pull on the dipping horizontal cable, which would pull down on the post, which would push down into the ground.

Diagraming Bridge Engineering

You can download a copy of the above bridge image here and print it out to discuss how pushing and pulling transfers the weight of the load. Ask your kids to use arrows to show where and how the bridges transfer weight.

Below is an example of what our kids came up with after we talked about it, showing how the bridge structure pulled and pushed to transfer the weight.

Create a Bridge Building Challenge!

Now that we adults know how bridges work, let’s see how our kids would approach this problem. We made a river across our LEGO Compatible Building Table. Sounds easy, but finding that many blue bricks took longer than we expected ;-). I think I did the last 1/3 by myself!

The challenge for your kids is to build a bridge, using only bricks, to cross the river. The bridge will then be tested to see how much weight it can hold. We made our river about 10” wide. Just long enough to make it a challenge.

Choose a Bridge Design

Discuss with your kids what type of bridge they would like to build and have them sketch their design on paper, showing once again how the bridge will transfer the weight.

With building bricks as the main construction material, an arch or beam bridge would be the most reasonable choice. The beam would be the easiest, but the arch would be the strongest. Choose wisely!

Build Time!

When the designs are complete, it’s time to build! The best advice for you on this section is NOT TO TAKE OVER, but to ask plenty of questions. It’s actually super interesting to see what the kids come up with but as they go, ask questions about how they think the weight will be distributed.

Testing the Bridge

Now comes the fun part! You’re going to need something to add as weight to the bridge. We used some hand weights but you can use big cans, gallons of milk... you may have to get creative! Have your kids guess how much weight their bridge can hold. It will probably hold more than they think (at least I hope so).

Start with the smallest weight, and add more weights, stacking them on top and holding them carefully in place.

Not that I recommend this at all (don’t try this at home), but I ended up standing the kids on top of the bridge and it actually held them!!! With full safety gear and and parental supervision of course! In the end, our bridge was strong enough to hold a 10 year old (for a few seconds). What do you think yours can do?

We'd love to see what your kids come up with if you give it a go at home! Please tag us @creativeqt on Facebook or Instagram!

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Creative QT designs quality + innovative toys that declutter homes and inspire creative play. Founded by parents of five, Adam and Dana Sue Hinkle, Creative QT’s vision is to empower parents and encourage a culture of families that Make Time Together. All products are designed to enrich families’ lives through active, creative play and play based learning. Creative QT products are laboratory tested for compliance with CPSC requirements and are free of lead, cadmium and phthalates so you can play with confidence. So, go ahead … today is the day: be your kid’s hero.

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