Math Investigations

Help with Opening PDF Files

Chapter 9

Part 1: For the problem in the Teacher's Edition, page 226

Provide students with the Problem Worksheet (PDF file)

Help students find a strategy for solving this problem. The following questions lead to a strategy for solving the problem:

  • What do we want to find out? (the weight of a female elephant)
  • What do we know? (A male elephant weighs about 14,000 pounds. Two male African elephants weigh about three times as much as a female elephant.)
  • How could we solve this problem? (Find the weight of two male elephants by multiplying 14,000 by two. Divide that number by three to find the weight of a female elephant.)

Answer:

Estimates will vary. Possible estimate: about 9,000 pounds

Part 2: Be an Investigator

A good time to do this investigation is after Lesson 2 on placing the first digit in the quotient.

Materials

  • graph paper

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

Ask: How can we find out how many pounds of food each one of these animals eats in a day? (Divide the number of pounds of food the animal eats in a given period of time by the number of days in that time period.)

Once students have calculated the number of pounds of food the animals eat in a day, talk to them about how to set up the bar graph. Because the range of numbers goes from 14 to 88, they probably won't want to use a 0, 1, 2, 3, etc. scale. A scale that goes by tens (0, 10, 20, etc.) would work nicely in this situation.

Answers:

A tiger eats about 360 pounds of food in nine days. (40 pounds a day)

A cow eats about 210 pounds of food in six days. (35 pounds a day)

A horse eats about 152 pounds of food in eight days. (19 pounds a day)

A cougar eats about 126 pounds of food in nine days. (14 pounds per day)

The answers for the bar graph will vary. Here is one possibility:

Survey Results:
How many pounds of food do animals eat per day?
Name of Animal Number of Pounds of Food
Tiger 4040
Cow 3535
Horse 1919
Cougar 1414

Student Report

The student report gives students an opportunity to show what they have done.


Houghton Mifflin Math Grade 4