Maryland Math 1.NOS.E.13.b

Math1st GradeNumber and Operation Sense

The Standard

1.NOS.E.13: Subtract a 1-digit number from a 2-digit number (without regrouping).

Use counting strategies, properties of operations, and/or the inverse relationship between addition and subtraction to subtract.

Maryland College and Career Ready Standards for Mathematics (2025) · USE PLACE VALUE UNDERSTANDING AND PROPERTIES TO ADD AND SUBTRACT.

Teacher's field guide

What Students Need to Do: Students find how many are left or missing in subtraction problems within 20. They count back, count up, break numbers apart, or use a related addition fact to find the answer.
What Mastery Looks Like: For 13 − 8, a student can count five jumps from 8 to 13 or use 8 + 5 = 13. They can show their steps on a number line and check the answer with addition.
Common Misconceptions: Some students count 8 as the first jump when counting up to 13 and answer 6. Others switch the numbers in a subtraction problem because they know they can switch numbers in addition.
How to Assess It: On an exit ticket, give students 14 − 9 = __. Ask them to show their steps on a number line and write an addition fact that checks their answer.

Lesson moves

Give pairs 13 counters and two ten-frames; have them remove 8, count what remains, and record 13 − 8 = 5.
Ask, 'How can 8 + 5 help you solve 13 − 8?' Have students draw and label their thinking.
Play fact-family memory with cards showing 12 − 7 = 5, 12 − 5 = 7, and 7 + 5 = 12; students match related facts.
Take 6 crayons from a set of 14 and place them in a cup; students write how many remain and explain their strategy.

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