Multiplying Fractions by Whole Numbers

Grade Levels: 3 - 8

INTRODUCTION
Students will use a recipe for applesauce cake to review the process of multiplying fractions by whole numbers.

SUGGESTED TIME ALLOWANCE
40 minutes

OBJECTIVES
Students will:

• recall how fractions are multiplied by a whole number.
• understand how to multiply to increase the yield of a recipe.

MATERIALS


• Worksheet #1 and Worksheet #2
• Web page: http://allrecipes.com/Recipe/Applesauce-Oatmeal-Cake/Detail.aspx

PROCEDURES

1. Review the following vocabulary: numerator, denominator, improper fraction, mixed fraction, yield.

2. Review with students how a fraction is correctly multiplied by a whole number.
   
   • Discuss how the whole number must be turned into a fraction, with the whole number as the numerator, and the number 1 as the denominator.
   • Also mention how mixed numbers, such as 1 1/2, must be converted into improper fractions to be multiplied.
   • Demonstrate the process: The numerators of the fraction and the whole number are multiplied together, as are the denominators of the fraction and the number 1. Give examples for some students to do. Mention that if an improper fraction results, discuss how it is correctly reduced.
   • Have students practice on the board and on their own.
     
     

3. Show students this recipe and read it over together: http://allrecipes.com/Recipe/Applesauce-Oatmeal-Cake/Detail.aspx. Inform them that a baker needs to make three Applesauce Oatmeal cakes. Although he is an excellent baker, she needs the class to figure out how much of each ingredient is needed.

4. Have students use Worksheet #1 and work with a partner to increase the recipe so that it will be three times as large.

5. If time allows, have students increase the recipe by 4, using Worksheet #2.

ASSESSMENT

See Worksheet Answer Keys.

EXTENSION ACTIVITIES

Use a supermarket advertisement or visit a grocery store to find the price of the ingredients listed and the size of the packages that are sold. Have students multiply to find the approximate price of each ingredient and for the three cakes.

Make the Applesauce Oatmeal cakes.

STANDARDS CORRELATION

Standards at McRel:

Solves real-world problems involving number operations (e.g., computations with dollars and cents)

Understands that numbers and the operations performed on them can be used to describe things in the real world and predict what might occur