Math Investigations

Help with Opening PDF Files

Chapter 16

Part 1: For the problem in the Teacher's Edition, page 380

Provide students with a copy of the Problem Worksheet (PDF file).

Ask the students the following questions to help them get started solving the problem:

  • What does the HO scale of 1:87 mean? (All measures on the model are 87 times smaller than on the actual car.)
  • How can you find the length of the HO scale model train to the nearest quarter inch? (Multiply the length of the actual train, 75 feet, by 12 to find the length in inches. Divide the product by 87.)

You can also ask similar questions for O scale and N scale.

HO scale: about 10 1/2 inches
O scale: about 18 3/4 inches
N scale: about 5 1/2 inches

Part 2: Be an Investigator

A good time to do this investigation is after Lesson 3 on distance, speed, and time.


  • calculators (optional)

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 the following questions to help the students get started doing the investigation.

  • Of distance, speed, and time, what is known and what is not known? (Time and distance are known and speed is not known.)
  • What formula would you use to find the speed? (s = d ÷ t)


Indy 500 Winners

Year Winner Time Converted
to Decimal
Speed (mph)
1990 Arie Luyendyk 2.686 185.981
1991 Rick Mears 2.833 176.457
1992 Al Unser, Jr. 3.718 134.477
1993 Emerson Fittipaldi 3.175 157.207
1994 Al Unser, Jr. 3.105 160.872
1995 Jacques Villeneuve 3.253 153.616
1996 Buddy Lazier 3.374 147.956
1997 Arie Luyendyk 3.424 145.827
1998 Eddie Cheever, Jr. 3.440 145.155
1999 Kenny Brack 3.264 153.176
2000 Juan Montoya 2.977 167.607
2001 Helio Castroneves 3.526 141.574
2002 Helio Castroneves 3.002 166.499
2003 Gil de Ferran 3.193 156.291

Student Report

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

Extending the Investigation

Have the students find the Indy 500 racecar driver with the fastest speed from 1990 on.

Houghton Mifflin Math Grade 6