The Golden Gate Bridge is an obvious example of a bridge. Have your students look for less noticeable bridges near their school. Click on the image for larger view.


Newspaper Bridges

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In the classroom, students become interested in exactly how much weight their bridge will hold. Students can go to the chalkboard to add together the weights of the books (or bodies) which their bridges would hold. In a fifth-grade class, the students took the weight of a book and multiplied it by the total number of books on the bridge. When they ran out of one type of textbook and had to use another, the problem became more complex.


One of the interesting ways to assess the bridges is to look at design efficiency. By efficiency, we mean how much newspaper it takes to hold up a pound of load. To find this, first determine the amount of newspaper used by weighing it. Then, divide the weight of the load by the weight of the bridge itself. The larger the result (load per unit amount of newspaper), the more efficient your bridge design.

Real Life

Students can look for bridges in the world around them. There are obvious examples, such as monuments like the Golden Gate, but there are many other less noticeable examples as well. Students can look for roads crossing creeks, pedestrian overpasses, or even second-story floors in their school. There are many books and videos which discuss the history and construction of bridges.

Build with Less

A natural extension of this activity is to ask the class: "What is the minimum amount of newspaper and tape that you would need to support one (or more) books?" Have the class try to build a "minimalist" bridge. This challenge should be preceded by a discussion of why one would wish to design a minimalist bridge. This could lead to discussions of "real world" considerations of cost factors in building. It also introduces a constraint that forces the students to look more closely at and apply what they have learned about what makes their bridges strong.

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