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Grade 3
. What Is It? Current Page:Tips and Tricks When Students Ask Lesson Ideas
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Tips and Tricks

Functional Relationships

  • Play the game "Function Machine" in class. Show students the following function table:

    input     output
    2     8
    5     11
    7     13
    9     ?
    12     ?
    15     ?

    The object is for students to find the output for the last three numbers by using the functional relationship between the input and output of the first three pairs of numbers. The functional relationship is that 6 was added to the input to arrive at the output, so the output for the last three numbers is 16, 18, and 15. Have students use other functional relationships and make their own function tables for the class to solve.

  • Have students write in their Math Journal about examples of functional relationships they see in their everyday lives.

  • Newspaper advertisements are a great resource. Have students bring advertisements to school that show functional relationships. Divide the class into groups to discuss the functional relationships they see in their ads. Then have each group present a summary of their findings to the class.

  • Encourage students to use different methods to find functional relationships. For example, a store sells video cassettes in packages of 3 for $9 and packages of 6 for $12. Which package is the better buy? One way to solve the problem is for students to find the unit cost of the video cassettes in each package - $3 for each cassette in the package of 3, and $2 for each cassette in the package of 6. They can then compare $3 to $2 to conclude that the package of 6 video cassettes is the better buy. Here is another method students can use to solve the problem: 6 is 2 times greater than 3, so compare the cost of 2 packages of 3 video cassettes to the cost of 1 package of 6 video cassettes. 2 times $9 is $18, $18 is greater than $12, so the package of 6 video cassettes is the better buy.
 

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