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1st Grade Math
2. 1.OA.A.2
2.1 Adding with 3 numbers up to 20
Adding with 3 Numbers up to 20
Discover simple strategies for adding three numbers up to 20, including grouping addends and making a ten, with easy step-by-step examples.
What You'll Learn
Add three addends together, such as \( 7 + 3 + 5 = 15 \), while keeping every sum at or below 20.
Apply the associative property to group addends in any order: \( (7+3)+5 = 7+(3+5) \).
Use the make-a-ten strategy by grouping two addends that sum to 10 before adding the third number.
Recognize doubles and near-doubles among the three numbers to speed up mental addition.
Compare different grouping paths to find the fastest way to reach the correct sum.
What You'll Practice
1
Solving three-number addition problems with sums up to 20
2
Adding combinations of single-digit numbers
3
Computing sums using both horizontal and vertical formats
Why This Matters
Adding three numbers builds your mental math skills and number sense, which you'll use daily when counting money, keeping score in games, or solving more complex math problems in school and real life.
This Unit Includes
1 Video lesson
Practice exercises
Learning resources
Skills
Addition
Three Addends
Mental Math
Number Sense
Basic Operations
OH Curriculum Aligned