Maryland Math 2.NOS.B.6
Standard Cluster
Recall or quickly derive addition and subtraction facts within 20. Use counting, make ten, and ten more/less, doubling strategies to add and subtract. 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. Use the inverse operation to add and subtract (e.g. think of 7 + ? = 15 to solve 15 – 7 = ?).
Maryland College and Career Ready Standards for Mathematics (2025) · ADD AND SUBTRACT WITHIN 20.
Cluster contents
Standards in This Cluster
2.NOS.B.6 is a cluster heading. These are the individual standards under it.
- 2.NOS.B.6.a
Use counting, make ten, and ten more/less, doubling strategies to add and subtract.
- 2.NOS.B.6.b
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.
- 2.NOS.B.6.c
Use the inverse operation to add and subtract (e.g. think of 7 + ? = 15 to solve 15 – 7 = ?).
Teacher's field guide
What This Cluster Means
What Students Need to Do
- Students answer addition and subtraction facts within 20 from memory or by finding a quick path to the answer. They count on, make ten, use ten more or less, use near doubles, and turn subtraction into a missing-addend problem.
What Mastery Looks Like
- A student can solve 9 + 7 by thinking 10 + 6 and 4 + 5 by thinking 4 + 4 + 1. They can solve 15 - 7 by asking what added to 7 makes 15.
Common Misconceptions
- Some students start counting at one instead of counting on from a number they know. Others change 9 + 7 to 10 + 7 without taking one from the 7. For 15 - 7, some answer 7 instead of finding the part left over.
How to Assess It
- On an exit slip, ask students to solve 9 + 7, 4 + 5, 15 - 7, and 16 - 10. Have them write or draw how they found each answer.
Lesson moves
Ways to Teach It
Give pairs two ten-frames and counters; build 9 + 7, move one counter to make ten, then record 10 + 6 = 16.
Ask students to write how 4 + 4 helps them solve 4 + 5, then explain their thinking to a partner.
Play a fact-card game with 8 + 3, 15 - 7, and 16 - 10; partners find answers and name their shortcuts.
Post a snack count of 15 apples with 7 taken; ask students to find how many remain using 7 + ? = 15.
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Printable 2.NOS.B.6 Worksheet
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Related Standards
- K.AT.A.2
Solve addition and subtraction problems in context (add to, take from, put together/take apart) within 10 and represent by using objects, drawings, and/or equat...
- 3.NOS.E.9
Recall or quickly derive multiplication and division facts within 100 (e.g., factors less than or equal to 10 and quotients less than or equal to 10).
- 4.NOS.C.7
Recall or quickly derive multiplication and division facts within 100 (e.g., factors less than or equal to 10 and quotients less than are equal to 10).
- 1.NOS.D.9
Recall or quickly derive addition and subtraction facts within 20.
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