What does it mean to add?
Addition means putting numbers together to find how many there are in all.
- 2 + 3 = 5
- 4 + 1 = 5
The answer to an addition problem is called the sum.
Adding three numbers
You can add three numbers to find one total. The order of the numbers does not change the sum.
- 2 + 3 + 4 = 9
- 1 + 5 + 2 = 8
You can add the numbers in any order to make it easier.
Making friendly numbers
A friendly number is a number that is easy to add, like 5 or 10. You can add two numbers first to make a friendly number.
- 3 + 7 + 4 → (3 + 7) + 4 = 10 + 4 = 14
- 6 + 4 + 5 → (6 + 4) + 5 = 10 + 5 = 15
Making 10 first can help you add faster.
Adding with sums up to 20
When adding three numbers, the sum can be 20 or less. All numbers you add can be from 0 to 9.
- 5 + 6 + 4 = 15
- 9 + 1 + 8 = 18
- 0 + 7 + 6 = 13
Adding zero does not change the total.
Using objects or drawings to add
You can use objects, pictures, or drawings to help you add three numbers.
- Draw 2 circles, 3 circles, and 1 circle. Count all the circles.
- Use cubes to show 4 + 5 + 2, then count them.
Counting carefully helps you find the correct sum.
Common Core alignment: CCSS.MATH.CONTENT.1.OA.A.2 – Add three whole numbers whose sum is less than or equal to 20.
Notes for teachers
This lesson is aligned with CCSS.MATH.CONTENT.1.OA.A.2. Use it for whole-class instruction, independent practice, or homework.
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