
Super Bridge


Classroom Activity

Objective
To recreate some of the challenges bridge builders face.
 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)
 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.)
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.
Organize students into
small teams and distribute the "Bridge Building" student handouts and materials.
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.
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?
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 cubelike 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.

