Hands-on Activity: Spaghetti Bridges

Contributed by: K-12 Outreach Office, Worcester Polytechnic Institute

A photograph shows a student-created truss-type bridge structure made with dry spaghetti noodles glued together.
Students design bridges made of spaghetti.
copyright
Copyright © 2007 FHKE (CC BY-SA 2.0), Flickr https://www.flickr.com/photos/fhke/1438930446/in/photostream/ https://creativecommons.org/licenses/by-sa/2.0/

Summary

Civil engineers design structures such as buildings, dams, highways and bridges. Student teams explore the field of engineering by making bridges using spaghetti as their primary building material. Then they test their bridges to see how much weight they can carry before breaking.

Engineering Connection

Many people in different branches of engineering work to build bridges. Civil engineers are responsible for design and construction of such structures, however they also work with mechanical engineers and material engineers to design the most stable structures. These engineers must consider many variables when creating plans, such as the distance to be spanned, where the bridge is being built, the expected type of traffic it will have to withstand, materials available, budget and what the bridge will look like.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

Suggest an alignment not listed above

Learning Objectives

  • To create a design method.
  • Group work and discussion.
  • Building techniques that civil engineers use.

Materials List

  • 1 pound dry spaghetti
  • glue gun
  • glue sticks, 1 package
  • various weights from 5 to 50 pounds
  • large tub (or newspapers to spread out), to make clean-up easier
  • 2 tables (place 1 foot apart)
  • metal strip (to serve as the road)
  • chain (to hold the weights)

Introduction/Motivation

Who do you think creates the human-made structures in our town? Who makes sure they are safe for us to use? (Listen to student ideas.) It is civil engineers who design and create structures such as buildings, dams, highways, skyscrapers and bridges.

We can explore the field of engineering by making bridges. We can then test them by applying weights to see when they break. Let's get started!

Procedure

  1. Show students the available "building materials," including the metal strip "road," chain and weights that will be used for testing.
  2. Divide the class into teams of students.
  3. Have teams draw their bridge designs on paper. Make sure that bridges are long enough to span a specified distance between two tables.
  4. Create the bridge using hot glue to hold it together.
  5. When the bridges are complete, test their strength. Place a bridge so it spans across the gap between two tables. Place a tub or spread-out newspapers under the bridge to catch falling debris and make clean-up easier.
  6. Put the strip of metal on the bridge (as the road). Then apply weights on the chain, starting with 5 pounds and working up to 50 pounds, or until the bridge breaks.
  7. Conclude with a class discussion to compare results and draw conclusions. Use the Investigating Questions as a concluding assessment.

Safety Issues

  • Be careful not to get burned from the hot glue and hot glue guns.
  • Wear safety glasses.
  • Beware of falling weights.

Investigating Questions

  • What happened when you added more weights? What does the bridge look like?
  • Does adding more height to the bridge make it stronger?
  • What are some ways to improve your design?

Assessment

Assign the Investigation Questions as a test, quiz or homework. Review students' answers to gauge their comprehension.

Have students record how much weight their bridges withstood before they failed. Then, as a class, create a histogram showing how much weight each bridge held. Discuss which design was able to carry the most weight and why (materials, geometry, use of glue, etc.).

Activity Scaling

For higher grades, add the additional requirement to incorporate into the design a truss system to strengthen the bridge structure. Incorporating a construction/assembly pattern makes the bridge sides and bottoms stronger. To help generate ideas, show students the example truss bridge designs in Figure 1. Point out how the designs are made from short straight pieces put together in patterns that often include triangles.

A line drawing shows side profiles of 1 different bridge types: Baltimore Truss, Baily Truss, Bowstring Truss, Camelback Truss, Warren Quadrangular or Lattice Truss, Whipple Truss, Parker Truss, Pennsylvania Petit Truss, Pauli or Lenticular Truss, Thatcher Truss. All the designs include repeated patterns composed of triangle shapes made from smaller straight pieces.
Figure 1. Example truss bridge designs.
copyright
Copyright © 2012 miser, Wikimedia Commons https://commons.wikimedia.org/wiki/File:Baltimore-truss.svg https://commons.wikimedia.org/wiki/File:Bailey-truss.svg https://commons.wikimedia.org/wiki/File:Bowstring-truss.svg https://commons.wikimedia.org/wiki/File:Camelback-truss.svg https://commons.wikimedia.org/wiki/File:Lattice-truss.svg https://commons.wikimedia.org/wiki/File:Whipple-truss.svg https://commons.wikimedia.org/wiki/File:Parker-truss.svg https://commons.wikimedia.org/wiki/File:Pennsylvania-truss.svg https://commons.wikimedia.org/wiki/File:Lenticular-truss.svg https://commons.wikimedia.org/wiki/File:Thatcher-truss.svg

Copyright

© 2013 by Regents of the University of Colorado; original © 2005 Worcester Polytechnic Institute

Supporting Program

K-12 Outreach Office, Worcester Polytechnic Institute

Last modified: November 16, 2016

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