Solving for Unit Rates (Introduction)

Learning Resource Type

Learning Activity

Overview

In this learning activity, students will learn a strategy for solving unit rate problems from the PBS video. In the accompanying classroom activity, students watch the video and then calculate and compare unit rates. The students will share solution strategies and consider ways that unit rates can facilitate making comparisons. To get the most from the activity, students should be comfortable finding equivalent fractions and have had some exposure to the concepts of ratio and unit rate.

Phase

Before/Engage
Mathematics (2019) Grade(s): 7

MA19.7.1

Calculate unit rates of length, area, and other quantities measured in like or different units that include ratios or fractions.

UP:MA19.7.1

Vocabulary

  • Unit rate
  • Ratio
  • Unit
  • Complex fractions

Knowledge

Students know:
  • What a unit rate is and how to calculate it given a relationship between quantities.
  • Quantities compared in ratios are not always whole numbers but can be represented by fractions or decimals.
  • A fraction can be used to represent division.

Skills

Students are able to:
Compute unit rates associated with ratios of fractional
  • lengths.
  • Areas.
  • quantities measured in like or different units.

Understanding

Students understand that:
  • Two measurements that create a unit rate are always different (miles per gallon, dollars per hour)

Learning Objectives

Students will be able to calculate unit rates in like or different units that include ratios or fractions. 

Activity Details

Procedure

1. Introduction (5 minutes, whole group)

  • The students will learn a strategy for solving unit rate problems from the PBS video.
  • The teacher will pair the students with a partner for partner work.
  • The teacher will distribute paper and pencils and pose the following problem for pairs to discuss:
  • Discussion: Store A sells notebooks at 2 for $5. Store B sells the same ones at 3 for $6. Which price is a better deal? How do you know?
  • Answer: After a moment, gather and record students’ solution strategies. If no one suggests setting the problem up as a comparison of ratios, do so yourself:

Image removed.

  • Ask students for examples of other unit rates. Prompt for a variety of contexts (e.g., pay per hour, distance per minute).

2. Watching the video (10 minutes, whole group)

  • Pause the video at 00:30 (30 seconds). Ask pairs to talk over the solution to the problem posed and jot down their solution strategies.
  • After a few minutes, resume the video. When it is over, ask students:
  • Did anyone solve the problem as in the video?
  • What other ways did you find to solve the problem?
  • Record students’ solution strategies or invite them to come up and do so. Emphasize the variety of possible approaches.

Assessment Strategies

The student responses during the class discussion will be used as a formative assessment. 

Background / Preparation

  • The teacher will need to sign up for a free PBS LearningMedia account.
  • To get the most from the activity, students should be comfortable finding equivalent fractions and have had some exposure to the concepts of ratio and unit rate.
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