NC.1.OA.2

Represent and solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20, by using objects, drawings, and equations with a symbol for the unknown number.

Step 1: Lesson Standards & Learning Goals

Unpacking Clarification

Students are expected to solve multi-step word problems by adding (joining) three numbers whose sum is less than or equal to 20, using a variety of strategies and mathematical representations that are described in NC.1.OA.1 and NC.1.OA.6.

Students may use concrete models or drawings to support their work on this standard before transitioning to using tools such as adding on a number line or number combinations (facts) to find the answers to these problems.

This standard provides rich opportunities for students to develop specific addition strategies as well as the commutative property of addition.

In Grade 1, one of the primary strategies is making a ten, so students should initially have ample opportunities to add three addends where two of the addends equal 10. Based on the commutative property of addition the addends can be arranged without changing the answer. When posing problems consider giving students problems where the first and third addend have a sum that is equal to 10. Examples include: 4 + 5 + 6, 2 + 3 + 8, and 3 + 4 + 7.

Sample Essential Questions

How can I represent and solve word problems with addition of three whole numbers whose sum is less than or equal to 20?

What tools can I use to help me solve word problems with addition of three numbers?
How can I write an equation to show three addends?

Vocabulary

add
addend
addition
total
sum

Students will be able to...

Solve multistep word problems by adding three numbers whose sum is less than or equal to 20.
- Use concrete models and drawings to support problem-solving.
- Transition to number lines and number combinations.
Develop specific addition strategies as well as the commutative property of addition.