Tacoma Narrows Bridge lesson plans - Math and Social Science

Math and Social Science

Aftermath – A new beginning: 1940 – 1950

Galloping Gertie lasted only four months and seven days before collapsing into Puget Sound in November, 1940. It became clear during those four months, however, that the Narrows Bridge was far more poplar than the expert's traffic surveys had predicted. In its first four months, the bridge's revenues fully justified a $10 million bridge, one that would have been four lanes wide, strong, sound, safe and still spanning the Narrows. For the residents of Tacoma and the Olympic Peninsula, the collapse of the bridge was a tragedy. Merchants on both sides lost income, and the military's vital link between the Bremerton Navy Yard and the Army's installations at McChord Field and Camp Lewis was all but severed. It took ten years before another bridge was built, due to insurance squabbles, the need for extensive testing, and the advent of World War II. But once the bridge was finally built, the number of vehicle crossings of the Narrows increased dramatically. Students will chart the traffic patterns across the Narrows over time, and use their graphs, prior historical knowledge and reasoning skills to answer the discussion questions listed below.

Lesson objectives

As a result of this lesson, students will be able to:

  1. Understand and apply properties of addition, subtraction, multiplication and division to real world problems;
  2. Understand and apply strategies and tools as appropriate to tasks involving the four basic operations on integers and non-negative rational numbers;
  3. Understand and apply various data display techniques, including bar, circle and line graphs;
  4. Understand how to devise a plan to solve problems.
  5. Use graphs to describe trends, compare, and interpret relationships from data.
  6. Understand how mathematical ideas connect within mathematics, to other subject areas, and to real-life situations.


Two days or class periods.

Materials needed:

Graph paper, rulers, calculators, drawing paper, and/or computers with PowerPoint and/or Excel. Provide students with data table shown below:

Year No. of Vehicles Annually
1930 ferry 171,993
1935 ferry 165,724
1939 ferry 205,842
1940 bridge (7-1 to 11-7) 265,748
1940 ferry 144,587
1945 ferry 480,009
1950 ferry 593,871
1950 bridge (10-14 to 12-31) 280,464
1955 bridge 1,715,135
1960 bridge 2,269,570
1965 bridge 4,112,455
1970 bridge 7,724,860
1975 bridge  
1980 bridge 14,225,145
1985 bridge  
1990 bridge 24,229,145
1995 bridge  
2000 bridge 32,120,000

Lesson steps

Day one:

1. Using the figures provided above, calculate the average number of vehicles crossing the Tacoma Narrows each day at five-year intervals beginning in 1930. For intervals that do not have yearly totals, calculate the average of the two surrounding intervals, and use that figure.

2. Calculate the percentage of growth from one interval to the next.

3. Make a graph showing the increasing numbers of vehicles crossing the Tacoma Narrows from 1930 to 2000.

4. Make another graph showing the rate of increase for each interval between 1930 and 2000.

5. Bring students together in a group and speculate on the reasons why the graph looks the way it does. See Tacoma Narrows Bridge website for more background information.

6. Tell students about the status of current construction on the second Narrows Bridge. Ask them what the implications are for future growth on the Olympic Peninsula.

Related links on this site:

Tolling history


Evaluate students' calculations and graphs based on the same standards you regularly use in your own classroom.