The Bridge as a Connection

Why were the
bridges built?

The Bridge as Machine

How did they
build the bridges?

The Bridge as Art

Why do the bridges
look like they do?
  People of the Bridge
Who designed
the bridges?

Tacoma Narrows Bridge Lesson Plans
Science Lab Activity

Construction of 1940 and Reconstruction in 1950

The purpose of this lab activity is to introduce the challenges of building a suspension bridge. Students will explore the engineering challenges of building the new Tacoma Narrows Bridge in 1950.

Lesson Objectives


  1. Develop an understanding of the design constraints engineers encounter when building a bridge
  2. Begin to understand the important of planning before building their bridge especially when supplies are limited.

Materials Needed:

  • 8 feet of string per group, a roll of masking tape, a cardboard box, pencil, scissors, pop-sickle sticks, sand or clay, books, and a piece of paper.

Lesson Steps

1. Students will break up into groups of four.

2. Each group will obtain their materials.

3. The group must construct a suspension bridge across two stacks of books with the materials listed above.

4. The group must sketch the bridge they built.

5. After the sketch is complete, the group will use the Narrows Bridge web site illustration of basic suspension bridge parts to label their drawing with the different parts of a typical suspension bridge.

6. The group will measure the following in inches:

  • Length of bridge
  • Length of center span
  • Height of towers from bottom to top
  • Width of deck on the bridge
  1. You may not talk to the group across from you.
  2. You cannot use any more material than what was given to you.
  3. Record any design changes you make when building your bridge and explain why this was necessary.
Post-Lab Activity:

The students should describe what they observed during this activity as well as some principles of physics. The similarities between engineering a bridge and building their model bridge will be noted.

Relating Mathematics:

Use the following measurements of the current Tacoma Narrows Bridge to have the students compare the measurements of their bridge to the real bridge. Incorporate scale factor. The Bridge Machine Since 1950 has “Span Statistics” that could be used in the classroom for fun facts:

Length:   5,979 feet
Length of center span:      2,800 feet
Width of the deck   46 feet 9 inches
Height of towers from the pier to the top of the tower:   467 feet

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