CCSS.Math.Content.1.OA.B
The standard
Understand and apply properties of operations and the relationship between addition and subtraction.
Common Core State Standards for Mathematics
What this standard means
Students need to see addition and subtraction as connected, not as separate tricks. They should use facts they know to solve new facts, such as using 6 + 4 to help with 4 + 6, or 10 - 6 to find the missing part in 6 + ? = 10.
Mastery looks like flexible thinking with objects, drawings, equations, and words. Students can explain why switching addends keeps the total the same, and why subtraction can check addition. Common trouble spots are treating the equal sign as “the answer comes next,” mixing up missing addends, and memorizing facts without understanding the parts and whole.
Ways to teach it
- Give pairs 10 connecting cubes and have them build two addend trains, switch the parts, then write both addition equations.
- Ask students to explain, “How can 8 - 5 help you solve 5 + ? = 8?” using a drawing.
- Show 7 + 2 = 9, 2 + 7 = __, and 9 - 2 = __, then ask students to fill in and explain.
- Use snack pieces or classroom supplies to model sharing a total into two groups, then write the matching addition and subtraction facts.
Plan a lesson for CCSS.Math.Content.1.OA.B
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Related standards
- CCSS.Math.Content.1.NBT.C
Use place value understanding and properties of operations to add and subtract.
- CCSS.Math.Content.2.OA.A
Represent and solve problems involving addition and subtraction.
- CCSS.Math.Content.1.OA.B.3
Apply properties of operations as strategies to add and subtract.
- CCSS.Math.Content.2.NBT.B
Use place value understanding and properties of operations to add and subtract.