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1. Compare how many scoops each bridge holds before collapsing. How many more scoops can the triangle truss bridge hold compared to the square truss bridge? Or is it the other way around?

2. What did you notice happening to the triangle-shaped trusses before they collapsed?

3. What did you notice happening to the square-shaped trusses before they collapsed?

Questions & Answers

What geometric shape is commonly used in bridge design?

Triangles are commonly used in bridge designs

Why is a triangle stronger than a square?

Triangles are stronger than squares because a force is evenly distributed from the vertex to the base of each side of the triangle, allowing them to remain stable. A square has a weak centre which collapses more easily.

Make it Your Own

In this science project, you were given specific directions for bridge designs to compare whether a square support system or a triangular support system would support more weight. Here are some other things to consider:

  • Build two bridges with the same design, but use different types of building materials, such as popsicle sticks, straws or Q-tips. Is one building material stronger than another?
  • Research bridge designs. Build two types of model bridges from toothpicks (or another similar material). Which design proves the strongest?
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    The glue needs to thoroughly dry (2-3 days) prior to testing the bridge's integrity and ability to bear a load.
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