- 35 non-bendy straws
- Clear tape
- Meter stick or yardstick
- 200 to 300 pennies
- Small cup
- Two chairs or tables
Build your bridge using only straws and clear tape. Before you build, you may want to sketch your design and test out shapes to see which are the strongest. For example, when you tape straw pieces together to make a square, should you leave the center empty, or add more straw supports in the center?
When you are satisfied with your bridge, place it between two tables or chairs that are space at least 9 inches apart. Place the cup in the middle and add a few pennies at a time. Count the pennies and keep adding them until the bridge collapses. How many pennies did it hold? How did the bridge break? Can you change your design to make it stronger?
The Museum of Science + Industry explains what is happening:
Look at a steel or wooden bridge and often you will see triangle shapes making up most of the bridge’s support structure. These are called truss bridges. Triangles are structurally the strongest shape because they allow weight to be evenly spread throughout a structure, allowing it to support heavy loads. Truss patterns are used in other structures as well, such as roofs, radio towers, crane arms, and more.
To learn more about bridges and other exciting engineering, check out these books!