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Instructor Overview

Students watch a video in which two students discuss the problem of how to compare fuel efficiency. Students then analyze the work of the two students as they use rates to determine fuel efficiency in two different ways.

Key Concepts

Fuel efficiency is a rate. Fuel efficiency can be expressed in miles per gallon (mpg). This rate is useful for determining how far a vehicle can travel using any number of gallons of gas. Fuel efficiency can also be expressed in gallons per mile (gpm). This rate is useful for determining how many gallons of gas a vehicle uses to travel any number of miles.

The rates miles per gallon and gallons per mile are inverse rates—they both describe the same relationship. For example, the rates 20 miles per gallon and 0.05 gallon per mile both describe the relationship between 300 miles and 15 gallons. The greater the rate in miles per gallon, the better the fuel efficiency. The smaller the rate in gallons per mile, the better the fuel efficiency.

SWD: Some students with disabilities will benefit from a preview of the goals in each lesson. This will help to highlight for students the critical features and/or concepts and will help them to pay close attention to salient information.

Goals and Learning Objectives

  • Explore rate in the context of fuel efficiency.
  • Express fuel efficiency as the rate miles per gallon (mpg) and as its inverse, gallons per mile (gpm).
  • Use the rate miles per gallon to find the number of miles a car can travel on a number of gallons of gas.
  • Use the rate gallons per mile to find the number of gallons of gas used for a number of miles driven.