1.OA.3

Standard

Apply properties of operations as strategies to add and subtract.2 Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.) To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.)

Student Language:

"I can use fact families to help me solve addition problems. (commutative)"
"I can use addition facts I know well to help me solve problems where there are more than two numbers. (associative)"

Explanation

About the Math, Learning Targets, and Rigor

This standard asks students to apply properties of operations as strategies to add and subtract. Students do not need to use formal terms for these properties.

Example

Student can build a tower of 8 green cubes and 3 yellow cubes and another tower of 3 yellow and 8 green cubes to show that order does not change the result in the operation of addition. Students can also use cubes of 3 different colors to prove that (2 + 6) + 4 is equivalent to 2 + (6 + 4) and then to prove 2 + 6 + 4 = 2 + 10. Students should understand the important ideas of the following properties:

Identity property of addition (e.g., 6 = 6 + 0)
Identity property of subtraction (e.g., 9 − 0 = 9)
Commutative property of addition: Order does not matter when you add numbers. (e.g. 4 + 5 = 5 + 4)
Associative property of addition: When adding a string of numbers you can add any two numbers first. (e.g., 3 + 9 + 1 = 3 + 10 = 13)

NOTE: Students need several experiences investigating whether the commutative property works with subtraction. The intent is not for students to experiment with negative numbers but only to recognize that taking 5 from 8 is not the same as taking 8 from 5. Students should recognize that they will be working with numbers later on that will allow them to subtract larger numbers from smaller numbers. However, in 1st grade students do not work with negative numbers.

1.OA.3

Standard

Explanation

Resources

Videos

Extra Practice