Thirteen Ed Online
Lesson Plans
Building Bridges
Overview Procedures for Teachers Organizers for Students


  • 11"x17" graph paper.
  • 1' rulers.
  • Pencils.
  • Wood glue. (Don't use hot glue, it stretches too much!)
  • Assorted string and fishing line. (Spyder wire, fishing line, and 3/32" nylon twine are great for suspension bridge cables.)
  • 1/2"x1/2", 3/4"x 3/4", 1/4"x 5" clear pine, assorted lengths (for bridges).
  • 3/4;"x 5" and 5/4"x 5" clear pine, (to construct frame for suspension and cable stayed designs).
  • Miter saw. (A power miter saw would be a big help.)
  • Assorted screws and screw eyes.
  • Assortment of weights totaling 300lbs.
  • Strong nylon twine to suspend weights from road surface.
Computer Resources:
You will need at least one computer with Internet access to complete this lesson. While many configurations will work, we recommend:

-- Modem: 28.8 Kbps or faster.
-- Browser: Netscape Navigator 3.0 or above or Internet Explorer 3.0 or above.
-- Macintosh computer: System 7.0 or above and at least 16 MBs of RAM.
-- IBM-compatible computer: 386 or higher processor with at least 16 MBs of RAM, running Windows 3.1. Or, a 486/66 or Pentium with at least 16 MBs of RAM, running Windows 95 or higher.

For more information, visit What You Need to Get Connected in wNetSchool's Internet Primer.

The following sites should be bookmarked:

  • Pre-engineering Software Corp.

    This site has information on truss bridge design, terms and definitions, force analysis, and even some interesting VRML bridges to view.

  • Truss Bridge Laboratory

    This University of Florida site has information about truss stability, modes of failure, and even plans for a simple bridge testing apparatus.

  • Bridge Basics

    A great site to get ideas for different style designs and to learn the basic differences between the various types of bridges.

  • Bridge Watching for Beginners

    A site from the UK, it contains information about bridge basics, forces and elasticity, and a full glossary and index of references.

  • Space Web Design

    A neat site about a design recently featured in POPULAR SCIENCE, gives insight into a bridge that may be able to be built at lengths currently unheard of. Great images to view!

  • What holds the balcony up in a cinema or theatre?

    This site takes students through a discovery activity to understand tension and compression forces as well as the principles behind cantilever bridge design.

  • The Academy

    University of Rhode Island's School of Engineering site with a great explanation of suspension bridge design.

  • Architectonics: The Science of Architecture

    Click on the "courseware" icon of this University of Oregon site and discover a series of lectures and labs explaining everything from stability and strength to testing methods. A truly academic site!


    Time Allotment:
    This lesson requires about fifteen class periods.

  • Design Brief and Criteria:

    Introduce the students to the design statement, resources, and other specific criteria from in the Design Brief, of Organizers for Students. Initiate a brief discussion by asking the question, "What are structures?"

  • Research:

    Give each student team a Research Log from the Organizers for Students. The students should visit each site and log in any information that is relevant to their design problem. Students should begin research using the sites listed on the Research Log. (Encourage your students to search for more information. This is just a start.)

  • Solutions:

    Students should sketch or download pictures of at least four possible designs for their chosen bridge style. They may also create their own designs. Students should then make notations on the designs, referencing any special features of the design. This should come from the information gathered during their Internet research.

    Teams should discuss the pros and cons of the designs they have found chosen. After comparing their choice to the design criteria, instruct them to select the one that will work best for the given situation.

    Have the teams complete a set of detailed, full size, working drawings of the design they have chosen. This should include dimensions and any other important information needed to build a model bridge.

  • Construction:

    When the teams complete the design phase of the activity, they should begin constructing the bridges using the tools and materials outlined in the Design Brief, in Organizers for Students.

  • Testing, Evaluation and Redesign:

    At the end of the construction phase, organize a testing session for the bridges. Try to make this a BIG DEAL in the classroom! Things like hard hats and other construction-type safety gear will lend to the excitement. Make sure you have enough safety glasses for ALL the students as pieces of the bridges may go flying off during the testing process. Video taping the experiments also makes for a good follow up, as you will be able to "stop frame" the bridges as they begin to fall. Students should record data as the testing takes place and make notations of the state of their bridges. Data from each design should be graphed to aid in comparing the different types of bridges.

    At the conclusion of testing, have each team compile their results and complete a portfolio that includes their research, design possibilities, chosen design with choice rational, any pre-construction sketches, and a summary and conclusion using the testing results for possible redesign.


    Science: Study torque and moments to help understand forces acting on structures.

    Social Studies: Study the history of bridges and how they helped with the westward expansion of the United States. Also, discuss the role bridges played with the expansion of the railroad.

    Language Arts: Have students give an oral presentation of their design to the class. Students should also turn in a documentation portfolio to reflect their work on this design investigation.

    Mathematics: Calculate a moment at the center of the bridge using the moment = force X distance method. Students enhance their knowledge of fractions by using rulers during the design and construction phases.


    One Computer in the Classroom
    If you have access to one computer in your classroom, you can organize your class in several ways. Divide your class into two groups. Instruct one of the groups to do paper research while the second group is working on the computer. Bring in books, encyclopedias, etc., from the library for the group doing paper research. When the groups have finished working, have them switch places.

    If you have a big monitor or projection facilities, you can do Internet research together as a class. Make sure that every student in your class can see the screen, then go to a relevant Web site(s), and review the information presented there. You can also select a search engine page and allow your students to suggest the search criteria. Again, bookmark and/or print the pages that you think are helpful for reference later.

    Several Computers in the Classroom
    Divide your class into small groups. Groups can do Internet research using pages you have bookmarked. Group members should take turns navigating the bookmarked site.

    You can also set up the class so that each computer is dedicated to certain sites. Students move around the classroom, and get different information from each station.

    Using a Computer Lab
    A computer center or lab space with a computer-to-student ratio of one to three is ideal for doing Web-based projects. Generally, when doing Web-based research, it is helpful to put students in groups of three. This way, students can help each other if problems or questions arise. It is often beneficial to bookmark sites for students ahead of time.

    Submit a Comment: We invite your comments and suggestions based on how you used the lesson in your classroom.

    Overview | Procedures for Teachers | Organizers for Students