Maryland Math 1.NOS.D.9.b
The Standard
- 1.NOS.D.9
- Recall or quickly derive addition and subtraction facts within 20.
Use the make ten strategy to add and subtract with combinations of 10 (e.g., 7 + 3, 6 + 4, 10 – 3, 10 – 6, etc.).
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 find the number that joins another number to make 10. They use that same pair to solve subtraction problems that start with 10.
What Mastery Looks Like
- Given 7 counters on a ten-frame, a student adds 3 and writes 7 + 3 = 10. They also use the frame to explain why 10 - 7 = 3.
Common Misconceptions
- Some students count 7 as the first added counter when solving 7 + 3. Others answer 7 for 10 - 7 because they name the counters taken away, not the counters left.
How to Assess It
- Show a ten-frame with 6 spaces filled. Ask students to fill in 6 + __ = 10 and 10 - 6 = __, then point to where each answer appears on the frame.
Lesson moves
Ways to Teach It
Give pairs a ten-frame and 10 counters; one student places 4 counters, and the other fills the empty spaces.
Ask: How does knowing 8 + 2 = 10 help you solve 10 - 8? Have students draw and explain.
Play a matching game with cards showing addition facts, subtraction facts, and ten-frames for the same pairs of numbers.
Put 10 crayons in a cup, then take out 6; ask students to predict how many remain and check by counting.
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Printable 1.NOS.D.9.b Worksheet
A ready-to-print activity worksheet aligned to 1.NOS.D.9.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.).
- 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.
- 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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