CCSS.Math.Content.2.NBT.B
The standard
Use place value understanding and properties of operations to add and subtract.
Common Core State Standards for Mathematics
What this standard means
Students need to add and subtract within grade-level ranges by thinking in hundreds, tens, and ones. They should use strategies like making a ten, decomposing numbers, using an open number line, and explaining why regrouping works.
Mastery looks like choosing a sensible strategy and showing the place value behind each step, not just following a written algorithm. Students often get stuck when a problem needs regrouping, when they forget that 10 ones make 1 ten, or when they line up digits incorrectly.
Ways to teach it
- Use base-ten blocks to model 47 plus 36, trade 10 ones for 1 ten, then record the matching equation.
- Ask students to explain which is easier, 82 minus 39 or 82 minus 40 plus 1, and why.
- Give three problems, 58 plus 27, 91 minus 46, and 300 minus 125, and ask for one drawn strategy.
- Use a classroom store receipt and have students find the total cost of two items or the change from one dollar.
Plan a lesson for CCSS.Math.Content.2.NBT.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.1.OA.B
Understand and apply properties of operations and the relationship between addition and subtraction.
- CCSS.Math.Content.4.NBT.B
Use place value understanding and properties of operations to perform multi-digit arithmetic.
- CCSS.Math.Content.3.NBT.A
Use place value understanding and properties of operations to perform multi-digit arithmetic.