Adding and Subtracting Within 20

1st Grade•15 minutes•CCSS 1.OA.C.6

Learning Objective

I can add and subtract within 20 using different strategies.

The commutative property states that in addition, numbers can be switched around and the answer will still be the same.

In the math mountain example, the total is at the top, and the partners or addends are at the bottom.

When adding more than two numbers, it can be helpful to make groups of doubles or tens to simplify the problem.

This lesson includes 3 practice questions to reinforce learning.

View questions preview

1. If 5 + 3 = 8, then what does 3 + 5 equal?

2. If 7 - 2 = 5, then what does 7 - 5 equal?

3. Which number goes in the blank: 4 + 6 + 2 = 10 + ___

Addition and Subtraction Strategies 1st Grade Math - Commutative and Associative Property

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