Math Investigations

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Chapter 9

Part 1: For the problem in the Teacher's Edition, page 190

As found on the Problem Worksheet (PDF file), ask the following questions to help the students figure out how much an animal would have to weigh to weigh about 1/4 as much as Sue, the T-Rex.

  • How could we find out a weight that is 1/4 the weight of Sue, the T-Rex? (Divide Sue's weight (seven tons) by three)
  • What could we convert seven tons to for the calculation? (Convert to pounds by multiplying 7 by 2000. 7 × 2000 = 14,000)
  • What is 14,000 divided by 3 rounded to the nearest thousand? (about 5,000 pounds)

Put students in groups of two to measure each other's height. Have students figure out the fraction of Sue's height that their height is and the fraction of the number of Sue's teeth that the number of their teeth is.

Answer:
weight: about 5,000 pounds
Possible answers: about 1/8 if height is five feet; 1/2 for about 30 teeth

Part 2: Be an Investigator

A good time to do this investigation is after Lesson 7 on using logical reasoning.

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

You may need to review Venn diagrams with the students. Go over what each region in the diagram means.

After students have done their own Venn diagram, have them trade diagrams so they can fill in the statements for a Venn diagram of another group.

Answers for the Data Sheet

  1. If a number is even and a multiple of three but not a multiple of five, it should go in Region      B.     
  2. If a number is even and not a multiple of three or five, it should go in Region      A.     
  3. If a number is even, a multiple of three, and a multiple of five, it should go in Region      E.     
  4. If a number is odd and a multiple of three and five, it should go in Region      F.     
  5. If a number is odd and a multiple of five but not three, it should go in Region      G.     

The Venn diagrams the students create will vary.

Student Report

The student report gives students an opportunity to show how they filled in the statements, and the Venn diagram with statements to go with it that they created.


Houghton Mifflin Math Grade 5