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Lesson on Bridges

Lesson on Bridges Building from a previous lesson that varied the thickness of a paper "bridge," this lesson is based on the data that student collect on the relationship between the length of a paper "bridge" and the number of pennies that can be supported by the bridge before it collapses. This exploration entails and inverse, non-linear relationship and helps students connect graphical and tabular representations and use them to make predictions about the breaking weight of other bridges.
Reflection Topics & Videos  Tasks
Discourse
Student Learning
Teaching Decisions
The Mathematics
Lesson Plan (PDF) Review the complete lesson plan and accompanying worksheets.
Student Work  View student work from this lesson.
Engaging in the Mathematics 

1. Suppose that a paper bridge 4" long can support a weight of 45 pennies and a bridge of 11" long can support a weight of 3 pennies. Construct a graph of this data, describing what is the independent variable and what is the dependent variable, and connect the two points with a line or a curve that you predict reflects the relationship between these two variables.

2. Based on your graph, explain in words, using mathematical language, exactly what happens to the breaking weight of a bridge as its length increases, assuming there is no change in its thickness.

About the Teacher  Nancy Barthel, 8th Grade
Folwell Middle School
Minneapolis, MN
Carla Steinbach, principal

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