Are you looking for some fun and engaging STEM activities for kids to try either at home or in the classroom?
Kids of all ages will have fun with this craft stick bridge STEM challenge.
Younger kids will enjoy building and then playing with the end product. Older kids can use this activity to learn about the different forces acting on bridges and why they are designed the way they are.
When it comes to STEM supplies to always keep on hand, craft sticks are a favorite. They are versatile, can be used for numerous projects, and are inexpensive. (I love getting ours at the Dollar Store.)
Besides using them to build bridges, a favorite for kids of all ages is making a craft stick catapult. If you haven’t tried that one yet, I highly recommend it.
Before starting this project, you may want to discuss a few different types of bridges with your child. This is perfect to do while driving — there are so many different types of bridges you can see!
A truss bridge is actually one of the oldest forms of modern bridges.
The sides on a truss bridge consists of a series of triangles, making it very strong.
Craft Stick Bridge
Materials Needed:
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- Craft Sticks (You need at least 80.)
- Hot Glue Gun
- Scissors
To create your own truss bridge with craft sticks, you will start by making 6 triangles.
Do this by arranging 3 craft sticks together to form a triangle, with their ends slightly overlapping. Hot glue them together. (Quick drying tacky glue is a great alternative for this STEM project, especially if you want to test how much weight your bridge can hold once it is built.)
Make 5 more triangles, just like the first one, until you have a total of 6.
Once you have your triangles made, set them aside. It’s time to make a base for the triangles to connect to.
Lay 3 craft sticks, end to end, in a straight line.
Cut another craft stick in half. Hot glue half of that craft stick on top of the first craft stick in your line of 3, making sure their curved ends are flush together. 
Take 2 more whole craft sticks and glue them onto the row, covering up the seams where the bottom craft sticks meet each other.
Finally, glue on the other half of the craft stick you cut in half.
Repeat this process, so you have 2 rows of craft sticks that have been glued together.
Once that is finished, hot glue the bottoms of 3 triangles to one of your rows of craft sticks. Repeat with the other 3 triangles and craft stick row.
To make the tops of your bridge’s sides, you will do a similar process.
Start by laying 2 craft sticks end to end.
Cut another stick in half and hot glue half of it on top of one of your 2 full craft sticks, making sure the curved ends match up.
Hot glue a full craft stick, making sure it touches the edge of your half stick and coveres up the seam of the bottom 2 craft sticks.
Then glue on the other half piece.
Repeat this process so you have 2 short rows of craft sticks glued together.
Now glue these short rows to the top portion of your triangles. This will complete your bridge’s sides.
Once your sides are complete, it is time to start building the bridge’s base.
Stand your sides up and hot glue one craft stick in the middle of your middle triangle on one of the sides to the other side. Make sure the craft stick lays flat.
Hot glue a few more sticks across the bridge’s bottom. I suggest placing one in the middle of each triangle, and one at the corner of each triangle. These will be supports for the bridge deck.
(The pic below was taken BEFORE we finished adding in all of the craft sticks at the bottom.)
To make a solid bridge deck that toy cars can travel on, you wil need to build a bridge deck.
Hot glue craft sticks perpendicular across those supports you just added. Make sure they touch side to side.
It took us 9 craft sticks to go from one side to the other.
You will repeat this process 3 times to make a solid base that is the entire length of your bridge.
For added strength at the top of your bridge, add a craft stick going across the middle. Then add a few more, spaced out evenly, going towards each end.
Once your bridge is complete, it’s time to test it out.
It’s perfect for driving small cars over.
But to make it even more of a STEM activity, you may want to challenge your child to see how much weight it can hold.
Craft Stick Truss Bridge
To test the strength of your bridge, place the bridge so its ends rest on 2 chairs.
Tie a small bucket to the middle of the bridge’s base.
Slowly fill the bucket with small weights, such as ankle weights.
If small weights aren’t available, you can also use sand to test how much weight it can hold. Just weigh the bucket of sand afterwards to determine how much it weighs.
Want to extend the activity?
Challenge your child to make a longer bridge and see how much weight it can hold.
Can they figure out how to construct it so it can hold the same amount of weight? Can they make it stronger?
How a Truss Bridge Works
Bridges have lots of forces that act on them. Gravity is one of those forces since bridges don’t have ground under them to help support them.
Bridges also have to deal with changing loads, not only do they have to support their own weight, but also the weight of whatever may travel over them, which is constantly changing. The triangle shape on a truss bridge helps with this.
Truss bridges use triangles to help make them stronger. Triangles are a very strong shape because the force added to a triangle gets spread out evenly on all 3 of its sides.
There are also several other factors that act on a bridge, such as tension (a force that stretches and pulls outward) and compression (a force that squeezes inward). In a truss bridge the triangle shapes help distribute these.
You can find out more about how different types of bridges work at Bridge Masters Inc.
If you liked this craft stick bridge STEM activity, you will also like:
- Craft Stick Rubber Band Shooter
- Mechanical Hand Made with Straws
- How to Make a Lemon Battery
- Build a Paper Cup Water Wheel
