Maryland Math 1.NOS.C.8

Math1st GradeNumber and Operation Sense

The Standard

Use the inverse relationship between addition and subtraction to subtract.

Maryland College and Career Ready Standards for Mathematics (2025) · UNDERSTAND AND APPLY PROPERTIES OF OPERATIONS AND THE RELATIONSHIP BETWEEN ADDITION AND SUBTRACTION.

Teacher's field guide

What This Standard Means

What Students Need to Do

Students use an addition fact to solve a subtraction problem. For 13 - 5, they find the number that makes 5 + __ = 13.

What Mastery Looks Like

A student says, “5 + 8 = 13, so 13 - 5 = 8.” They use the same method with new numbers and explain their answer with cubes or a drawing.

Common Misconceptions

Some students add the numbers in the subtraction problem instead of finding the missing part. Others change 13 - 5 into 5 - 13, even though 13 is the whole.

How to Assess It

On an exit ticket, write 14 - 6 = __ and 6 + __ = 14. Ask students to fill both blanks and tell how the addition fact helped.

Lesson moves

Ways to Teach It

  1. Give pairs 13 cubes; have them remove 5, count what remains, and write matching addition and subtraction equations.

  2. Ask, “If 7 + 6 = 13, what is 13 - 7, and how do you know?”

  3. Play fact-family match: students pair cards showing 9 + 4 = 13 and 13 - 9 = 4, then explain each match.

  4. Put 12 crayons in a box, take out 5, and ask students to use 5 + __ = 12 to find how many remain.

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Printable 1.NOS.C.8 Worksheet

Preview of the 1.NOS.C.8 printable worksheet

A ready-to-print activity worksheet aligned to 1.NOS.C.8, with an answer key for the teacher on its own page. No account needed.

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