Not So Fast : A Lesson by Mathalicious

In most places, fines for speeding are calculated according to how many miles-per-hour over the speed limit a driver is moving. But does that make sense? Is driving 80 in a 60 really the same as driving 40 in a 20? If not, is there a better way to determine speeding penalties?

In this lesson, students learn how speeding tickets are calculated and use linear functions in order to compare a few different proposals and figure out the fairest way to keep the highways safe.

Students will

Given the recorded speed and speed limit, evaluate a linear function to calculate a fine
Using the fine amount and speed limit, solve for how fast the fine recipient must have been driving
Create graphical representations from verbal descriptions of a linear relationship
Compare models for speeding fines, and determine when each would be favorable for drivers

Before you begin

Students should have a basic understanding of linear relationships, including how to move back and forth among verbal descriptions, equations, and graphical representations of those relationships. Some of the driving scenarios presume that students will be able to use percent change as a basis of comparison.