Maryland Math 2.NOS.B.6.b
The Standard
- 2.NOS.B.6
- Recall or quickly derive addition and subtraction facts within 20.
Use the use ten strategy (e.g., think of 9 + 1 + 6 to solve 9 + 7) and doubles plus one strategy (e.g., think of 4 + 4 + 1 to solve 4 + 5) to add and subtract.
Maryland College and Career Ready Standards for Mathematics (2025) · ADD AND SUBTRACT WITHIN 20.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students break numbers apart to make ten when adding or subtracting within 20. They also use a double they know to solve a nearby fact with one extra.
What Mastery Looks Like
- For 9 + 7, a student writes 9 + 1 + 6 = 16 and explains where the 1 came from. For 9 - 4, they use 4 + 4 + 1 = 9 to see that 5 is left.
Common Misconceptions
- Some students split 7 into 1 and 6, then add the 1 twice. Some stop at 10 when subtracting 7 from 15, forgetting to subtract 2 more. Others say 9 - 4 = 4 because they ignore the extra 1 in 4 + 4 + 1.
How to Assess It
- Exit ticket: Solve 9 + 7 by making ten and 9 - 4 using a double. Write the number sentence that helped with each answer.
Lesson moves
Ways to Teach It
Use ten-frames and counters for 9 + 7: move one to make ten; for 15 - 7, remove five, then two.
Ask partners, 'How does 4 + 4 help you find 4 + 5 and 9 - 4?' Have them draw dots to explain.
Deal fact and strategy cards, then match 9 + 7 to 9 + 1 + 6 and 9 - 4 to 4 + 4 + 1.
Put 9 markers in a cup, add 7 more, and ask students to move one marker to make a group of ten.
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Printable 2.NOS.B.6.b Worksheet
A ready-to-print activity worksheet aligned to 2.NOS.B.6.b, with an answer key for the teacher on its own page. No account needed.
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Related Standards
- 1.NOS.D.9.a
Use the count on and count back strategies to add and subtract (e.g., 4 + 1, 7 – 2, etc.).
- 1.NOS.D.9.b
Use the make ten strategy to add and subtract with combinations of 10 (e.g., 7 + 3, 6 + 4, 10 – 3, 10 – 6, etc.).
- 2.NOS.B.6.a
Use counting, make ten, and ten more/less, doubling strategies to add and subtract.
- 1.NOS.D.9.c
Use the ten more and ten less strategies to add and subtract (including those with a difference of 10).
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