Math Investigations

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Chapter 13

Part 1: For the problem in the Teacher's Edition, page 332

Provide students with the Activity Page (PDF file).

Before students begin this activity, brainstorm with them ways they could earn money. Talk about how much they could charge to different kinds of work. Tell them to be sure to show how they figured out how long it would take them to earn $100.

Answers will vary.

Part 2: Be an Investigator

A good time to do this investigation is after Lesson 2 on multiplying whole numbers and decimals.

Introducing the Investigation

Introduce the investigation by reading aloud the assignment at the top of the first page of the Description of Investigation and Student Report (PDF file), by having one of your students read aloud the assignment, or by having the students read the assignment individually.

Put students in groups of two to four to work on the investigation.

Doing the Investigation

After students have completed the activity, ask the following question:

  • Why wouldn't you always choose Job B, since it pays more per hour than Job A? (Because if you work enough hours more in Job A than Job B, you can earn more money.)

Answers for the Data Sheet

Would you choose Job A for 10 hours or Job B for 5 hours?

  • Job A for 10 hours: $8.55 × 10 = $85.50
  • Job B for 5 hours: $15.34 × 5 = $76.70
  • Job A is the choice where you will earn the most money.

Would you choose Job A for 12 hours or Job B for 7 hours?

  • Job A for 12 hours: $8.55 × 12 = $102.60
  • Job B for 7 hours: $15.34 × 7 = $107.38
  • Job B is the choice where you will earn the most money.

Student Report

The Student Report gives students an opportunity to show what they have done and communicate about mathematics.


Houghton Mifflin Math Grade 5