Building Bridges

Born on June 13, 1806: John Augustus Roebling, an engineer especially known for suspension-style bridges and the design of the Brooklyn Bridge. From straws to balsa wood to egg shells, students can get hands-on this summer exploring and testing bridge construction. In an episode of the "Magic School Bus," Ms. Frizzle's class experimented with gum drops and toothpicks. What will you use? (Image Source: Wikipedia)

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A classic Magic School Bus episode involves making a bridge out of materials found in the bathroom in order to cross the bathtub, in which an alligator is lurking. To complicate matters, Ms. Frizzle's class has been shrunk! At two inches tall, the span of the bathtub seems about the size of the Grand Canyon!

Making Connections

Connected building blocks stacked vertically make a tower. But the same connected stack stretched side to side between two elevated objects creates a bridge.... and brings up bridge-related problems, like sagging! Shorten the distance of the bridge, and you may minimize the sagging. But if you need to span a bigger area, what can you do?

Tinkering with concepts of bridge design and principles of structural engineering is something students can explore alone or in teams, and summer is a great time to gather household supplies, and see what works. Bridge building offers a creative activity, a brain teaser, and an engineering project all wrapped up in one. Make it a challenge! Which kind of bridge is strongest? How can you test bridge strength? How can various kinds of bridges be reinforced to increase their strength? Which type of bridge holds up best in an earthquake? How wide can the bridge be before and remain strong?

In Action

For hands-on fun with bridges and an introduction to structural design, check out the following Science Buddies science fair project ideas:

• The Effect of Bridge Design on Weight Bearing Capacity
• Bridges That Can Take a Shake!
• Keeping You in Suspens(ion)
• The Design Process: Creating a Stronger Truss
• Fallen Arches: The Surprising Strength of Eggshells
• Paper Bridge for Pennies*
• The steps of the Engineering Design Process can help you think about how to approach designing a bridge for a specific use. Put your ideas on paper and get started!
• For a video look at bridges, watch DragonFly TV's "Bridge Building Club", which follows a middle-school team's efforts at designing and testing a balsa wood bridge.