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Super Bridge
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Classroom Activity
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Objective
To recreate some of the challenges bridge builders face.
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copy of "Bridge Building" student handout (PDF
or
HTML)
- coffee can
- 75 uncooked spaghetti noodles
- 2m (6.5ft) masking tape
- standard set of weights (fishing sinkers work well)
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6 strips of corrugated cardboard:
8 cm x 30 cm (3 in. x 12 in.)
8 cm x 50 cm (3 in. x 20 in.)
8 cm x 80 cm (3 in. x 31 in.)
8 cm x 100 cm (3 in. x 39 in.)
8 cm x 120 cm (3 in. x 47 in.)
8 cm x 150 cm (3 in. x 59 in.)
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One of the major challenges bridge designers face is
constructing towers to support the bridge. In this activity,
students build structures that recreate problems bridge builders
face.
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Organize students into small teams and distribute the "Bridge
Building" student handouts and materials.
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Have students design and build a tower structure using uncooked
spaghetti that will support a coffee can. Have them find the
maximum length of cardboard road the structure supports, add
weights to their structures, and find the maximum road lengths
again.
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After each team has completed their structure, have the class
compare and analyze each team design. Which design holds the
most weight? How could the design that holds the least weight be
improved? Which design balances the longest road? Which designs
appears to twist and turn under weight? Which designs prevent
twisting?
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After analyzing each design, have students suggest two ways they
would improve their designs.
Students may begin by placing individual pasta strands around the
base of the can or by building a cube-like structure as shown below.
Students will discover that the best way to enhance the strength of
pasta and prevent torsion is to make bundles of noodles and to use
triangulation. The triangle shape, in combination with the bundles
of noodles, greatly improves the tensile and compressive strengths
of pasta. By adding weight to the can, students will find that the
length of road the structure can support increases. The weight
increases stability by compressing each leg of the triangle on its
adjoining legs and preventing the materials from twisting.
Adding weight to the coffee can stabilizes the base of the bridge
tower, which in turn stabilizes the cable structure that holds up
the road. The weight prevents torsion of the tower and also acts as
a huge compressive force so that the entire tower stays in place.
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