Maryland Math 2.NOS.C.8.c
The Standard
- 2.NOS.C.8
- Fluently add and subtract within 100.
Determine and explain when a strategy is most efficient.
Maryland College and Career Ready Standards for Mathematics (2025) · USE REPRESENTATIONS, PLACE VALUE UNDERSTANDING, AND PROPERTIES OF OPERATIONS TO ADD AND SUBTRACT.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students solve addition and subtraction problems and compare ways to get the answer. They choose a method that fits the numbers and explain why it takes fewer or simpler steps.
What Mastery Looks Like
- For 52 - 49, a student counts up 3 instead of regrouping to subtract. For 46 + 32, they add tens and ones and explain why that is easier than counting by ones.
Common Misconceptions
- Some students use the same method for every problem, even when the numbers suggest an easier one. Others think counting from one is necessary for 49 + 3.
How to Assess It
- Exit ticket: Solve 52 - 49 and 46 + 32. For each, show your method and explain why you chose it.
Lesson moves
Ways to Teach It
Give pairs base-ten blocks for 49 + 3; have them trade ten ones for a ten, then compare with counting on three.
Ask, “Would you count up or subtract by place value for 52 - 49?” Have students show both and explain their choice.
Make cards for 48 + 2, 46 + 32, and 52 - 49; partners draw one, choose a method, and justify it.
Set a pencil price at 49 cents; give pairs 52 play cents and ask which method finds the change with fewer steps.
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Printable 2.NOS.C.8.c Worksheet
A ready-to-print activity worksheet aligned to 2.NOS.C.8.c, with an answer key for the teacher on its own page. No account needed.
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Related Standards
- 3.NOS.D.7.c
Determine and explain when a strategy is most efficient.
- 6.NOS.B.3.d
Determine and explain when a strategy or algorithm is most efficient.
- 4.NOS.B.3.d
Determine and explain when a strategy or algorithm is most efficient.
- 5.NOS.B.4.d
Determine and explain when a strategy or algorithm is most efficient.
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