Build a Bridge for a Toy Squirrel: Fall STEM Challenge for Kids

A toy squirrel bridge challenge asks kids to span a 12-inch gap between two book stacks with craft sticks and tape, then load it with pennies until it fails. The winning fix is a triangle truss: sticks taped into triangles hold far more weight than a flat beam. Plan 45 minutes for 3 rounds. Ages 6 to 10.

What do you need for the squirrel bridge challenge?

Supplies

• at least 40 craft sticks (standard 4.5-inch popsicle sticks)
• masking tape (1 roll)
• yarn or string (about 3 feet)
• scissors
• ruler
• books (two stacks of sturdy books for the bridge supports)
• small toy squirrel or a pinecone stand-in
• at least 20 pennies
• small cup or bowl (to hold the pennies)
• paper
• pencil

If you do not have a toy squirrel, a pinecone works as the stand-in. Pick one that sits flat so it does not roll off mid-test.

How do you build the bridge?

Build on the floor so the book stacks cannot topple onto anyone.

1. Stack two equal piles of books 12 inches apart, each stack about 4 inches tall. Measure the gap with the ruler to check.
2. Make long beams: overlap 4 craft sticks by 1 inch, end to end, and tape each joint on both sides. Each beam ends up about 15 inches long. Make 8 beams.
3. Lay the 8 beams side by side across the gap to form the deck. Tape across both ends of the deck with 2 strips of tape to hold the beams together.
4. Set the toy squirrel or pinecone in the middle of the deck.

This is the same build, test, and improve loop as the windproof paper scarecrow, just with sticks instead of paper.

How do you test the bridge?

1. Keep the pennies in the small cup. Place the squirrel in the middle of the deck.
2. Add pennies one at a time onto the middle of the deck, stacking them in a small pile. Count out loud as you go.
3. The bridge fails when the deck touches the floor or a joint breaks apart. Stop and record the penny count on the paper with the pencil.
4. Run 3 rounds minimum: round 1 tests the flat beam deck, round 2 adds triangle trusses, and round 3 is your improved design.

To build the triangle truss for round 2, tape craft sticks into a row of triangles along each side of the deck and tape every corner. Triangles do not squish flat the way squares do, so the truss sides stop the deck from sagging in the middle. Kids who liked counting and comparing in the corn kernel measuring lab will feel right at home tallying pennies here.

What goes wrong and how do you fix it?

• Middle sags under the pennies: add the triangle truss to both sides. This is the tested fix and it holds far more weight than the flat deck alone.
• Sticks slide apart at the joints: tape every joint on both sides, not just the top. Wrap the tape all the way around the joint.
• Tape stretches or peels: use shorter strips pulled tight, or lash the joint with yarn tied in a square knot.
• Beams too short and the ends slip off the books: rebuild the beams overlapping only half an inch, or add a fifth stick to each beam.
• Book stacks wobble: rebuild with the biggest books on the bottom, on the floor.
• Pinecone squirrel rolls off: wedge it in place with a small loop of tape, sticky side out, under the pinecone.

My first flat deck folded at 11 pennies when one taped joint peeled open in the middle. I re-taped every joint on both sides, added the triangle sides, and the same deck held 47 pennies with the squirrel still sitting pretty. Taping both sides of every joint did half the work.

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Frequently Asked Questions

What age is this for?

Ages 6 to 10. Six and 7-year-olds build best with an adult partner handling the scissors and helping tape tricky joints, while 8 to 10-year-olds can run all three rounds mostly solo. Younger kids love loading the pennies and counting the results, but the truss triangles need the fine motor control of school-age hands.

How messy does it get?

Almost none. This is a dry build with sticks, tape, and pennies on the floor, so cleanup is picking up tape scraps and dropped pennies. Keep the pennies in the small cup between rounds so they do not scatter across the room. Do a final penny sweep at the end, since a penny underfoot is no fun for bare feet.

How long does it take?

Plan 45 minutes for 3 full rounds: 15 to build the flat beam deck, 10 to test and count pennies, 10 to add the triangle trusses, and 10 to improve and run the final test. Kids who get hooked keep reinforcing and retesting past the third round, which is exactly the engineering loop you want them practicing.

Is it safe for young kids?

Scissors stay in adult hands: an adult cuts the tape strips and yarn, or supervises closely while an older child cuts. Pennies are choking hazards for children under 3, so younger siblings stay out of the test zone. Build on the floor so the book stacks cannot topple onto anyone, and set the no-stepping rule before the first test begins.

Be safe and have fun!