N2C3TNp18

 

Answer to Problem 18:

0

 

DEFINITIONS:

commutative property of addition—the sum stays the same when the order of the addends is changed.
Example: 6 + 4 = 4 + 6.[1]

identity property of addition—if you add a zero to a number, the sum is the same as that given number.
Example: 7 + 0 = 7.[2]

 

Teacher Notes:

The uses of the commutative property of addition will often arise when students are given the opportunity to use their own strategies for adding several numbers. Once they have more than two numbers, they are also using the associative property of addition (sum stays the same even if the order of two or more addends is changed).

 

At this level, teachers should use the terms “commutative” and “identity” properties. It is not expected that all students will use these terms.


 

[1] Math at hand: A mathematics handbook (p. 519). (1999). Wilmington, MA: Great Source Education Group, Inc.

[2] Math at hand: A mathematics handbook (p. 525). (1999). Wilmington, MA: Great Source Education Group, Inc.