Rainbow Strongest Bridge Challenge Challenge
⚠️ Safety Warning
Allow proper drying time for glue joints. Be careful when testing with heavy weights — have an adult supervise.
All experiments require adult supervision.
Materials You'll Need
Gather these 7 items before starting
💡 Tip: Check off items as you gather them to stay organized!
Step-by-Step Instructions
Follow these 8 steps carefully
For this rainbow version, research different bridge designs: beam, arch, truss, and suspension.
Plan your bridge design on paper first — it must span at least 30cm.
Build the bridge sides first: create triangular truss patterns with popsicle sticks and glue.
Let each section dry completely on wax paper, using binder clips to hold joints.
Connect the two sides with cross-bracing sticks for lateral stability.
Build the road deck by gluing sticks across the top.
Place the bridge between two equal-height boxes with the span unsupported.
Gradually add weight to the center. How much can your bridge hold before breaking?
✅ Remember: Take your time with each step and ask an adult for help if needed!
The Science Behind It 🔬
Bridge engineering is all about distributing force! A triangle is the strongest geometric shape because it cannot be deformed without changing the length of one of its sides. That is why truss bridges use triangular patterns. When weight pushes down on the bridge, the force travels through the structure to the supports. Arch bridges are strong because they convert downward force into outward compression along the arch curve. Real bridge engineers must consider not just weight, but wind, earthquakes, traffic vibration, and temperature changes. Some bridges can support 100 times their own weight! This variation explores the concept further by introducing new variables and measurements.