Math Investigations

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Chapter 7

Part 1: For the problem in the Teacher's Edition, page 170

Students can practice their research skills by finding data on a career they are interested in, or you can provide them with the data sheet that gives information on different careers found in the Problem Worksheet (PDF file).

Ask students to write the answers to the problems they write.

If students use the data we have provided they might ask what the annual salary is of each career. For the cosmetologist, the photographer, and the astronomer, they would multiply the average weekly salary by 52, since there are 52 weeks in a year. For the forest and conservation worker and the firefighter, they would multiply the average monthly salary by 12, since there are 12 months in a year.

If students find their own data, the problems they write will depend on the information they find.

Part 2: Be an Investigator

A good time to do this investigation is after Lesson 6 on multiplying three-digit numbers by two-digit numbers.

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

Discuss the predictions students made with the class. Many students may have predicted that Mio would win total sales because she sells the highest-selling bike. Ask students why Mio did not win even though she sells the highest-selling bike. Bring out in a discussion that you can often make more money selling many inexpensive items than selling a few expensive items.

Name of Salesperson Price of Bicycle they Sell Number of Sales for One Month Period Total Sales
Karen $208 36 $7,488
Joe $115 73 $8,395
Roberto $316 24 $7,584
Mio $392 20 $7,840
Lucinda $195 56 $10,920

The salespeople in order of the price of the bicycle they sell from least to greatest is: Joe, Lucinda, Karen, Roberto, Mio.

The salespeople in order of total sales for the month from least to greatest are: Karen, Roberto, Mio, Joe, Lucinda.

Student Report

The letter back to Carol Kennedy gives students an opportunity to show what they have done.

Extending the Investigation

Have students figure out how many bicycles each salesperson would have had to sell to bring in the same amount of money as Lucinda or more. You may want to provide calculators for this extension. There are at least two ways to do this:

  1. Divide Lucinda's total sales by the price of each salesperson's bike.
  2. Keep adding the price of the bike to the salesperson's total sales. Keep track of how many times you added to get sales equal to or greater than Lucinda's.

Houghton Mifflin Math Grade 4