Math Investigations

Help with Opening PDF Files

Chapter 2

Part 2: For activity in Teacher's Edition, page 22

Students can practice their research skills by finding facts about the Grand Canyon that contain numbers greater than one thousand. Or you can provide them with the data sheet found in the Activity page (PDF file).

If students have researched their own data, have them share what they have found.

Have students share the numbers in their facts about the Grand Canyon and show the digit that they underlined that is in the thousands place.

Answers for Data Sheet:

  • The area of Grand Canyon Park is 1,218,376 acres or 1,904 square miles.
  • The South Rim of Grand Canyon is approximately 1,200 feet lower than the North Rim of Grand Canyon.
  • The average elevation of the North Rim is about 8,000 feet.
  • The walls that make up the top part of the Grand Canyon are 250,000,000 years old.
  • In 1993, almost 5,000,000 people visited the Grand Canyon.
  • In 1919, only 44,000 people visited the Grand Canyon because of World War I.

Part 2: Be an Investigator

A good time to do this investigation is after Lesson 5 on rounding numbers.

Introducing the Investigation

Introduce the investigation by reading aloud the assignment on 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 students to work on the investigation. You may choose to have the students research facts about the Grand Canyon or you can provide them with the data sheet found on the Description of Investigation and Student Report (PDF file) on the Grand Canyon.

Doing the Investigation

Have students share the articles they wrote and the rounded and exact numbers that they used in their articles.

Student Report

Students should put the final draft of their article in this section.

Extending the Investigation

Have students research another travel destination and write an article about it that contains both rounded numbers and exact numbers.


Houghton Mifflin Math Grade 4