Math Investigations

Help with Opening PDF Files

Chapter 11

Part 1: For the problem in the Teacher's Edition, page 280

Help students get started with this Problem Worksheet (PDF file) with the following questions.

Tell the students that Gil de Ferran had the winning time of the Indy 500 in 2003 at 3.193 hours, or look up the winning time of the most recent Indy 500.

Ask the following questions to help students do this activity:

  • What was the winning time in 2000? (2.983 hours)
  • Is the winning time in 2003 more or less than the winning time in 2000? (more)
  • What is the difference between the winning time in 2003 and the winning time in 2000? (0.210 hours)

Part 2: Be an Investigator

A good time to do this investigation is after Lesson 3 on subtracting 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 students to work on the investigation.

Doing the Investigation

Be sure students understand the importance of writing the zero before the decimal point in a decimal less than one. Because decimal points are so small, the zero before the decimal point brings people's attention to it.

Answers for the Data Sheet

  • The difference between Al Unser's winning times in 1970 and 1971 is           0.37 hours.          
  • The difference between Al Unser's winning times in 1971 and 1978 is           0.77 hours.          
  • The difference between Al Unser's winning times in 1978 and 1987 is           0.015 hours.          
  • The difference between Al Unser, Jr.'s winning times in 1992 and 1994 is           0.613 hours.          
  • Al Unser's best time was in           1987.          
  • Al Unser, Jr.'s best time was in           1994.          
  • The difference between Al Unser's best winning time and Al Unser, Jr.'s best winning time is           0.28 hours.          

Student Report

The letter back to Lou Franco gives students an opportunity to show what they have done.

Extending the Investigation

Have the students research other information about the Indy 500 and write questions that involve the addition or subtraction of decimals.


Houghton Mifflin Math Grade 5