Georgia 1.NR.2.3
The Standard
Recognize the inverse relationship between subtraction and addition within 20 and use this inverse relationship to solve authentic problems.
Georgia's K-12 Mathematics Standards · Explain the relationship between addition and subtraction and apply the properties of operations to solve real-life addition and subtraction problems within 20.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students connect addition and subtraction as opposite operations. They use a known addition fact to solve a subtraction problem within 20 and explain their reasoning.
What Mastery Looks Like
- A student can solve a missing-part problem within 20 using addition or subtraction. The student writes a related equation, such as 7 + 5 = 12 for 12 − 7 = 5, and explains the connection.
Common Misconceptions
- Students may treat addition and subtraction as unrelated steps. They may reverse subtraction numbers or assume subtraction always makes the first number smaller without considering the situation.
How to Assess It
- Give this exit ticket: “There are 13 birds. Some fly away, and 8 remain. How many flew away? Show a related addition equation.”
Lesson moves
Ways to Teach It
Give pairs 20 counters and cups, then have them hide part of a set and use addition to find the hidden amount.
Ask students to explain in words how 9 + 6 = 15 can help solve 15 − 9.
Play a fact-family match game using cards with related addition equations, subtraction equations, and picture models.
Set up a class store where students find how many items were sold by comparing the starting amount with the amount left.
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Printable 1.NR.2.3 Worksheet
A ready-to-print activity worksheet aligned to 1.NR.2.3, with an answer key for the teacher on its own page. No account needed.
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Related Standards
- 1.NR.2.1
Use a variety of strategies to solve addition and subtraction problems within 20.
- 1.NR.2.7
Apply properties of operations as strategies to solve addition and subtraction problem situations within 20.
- 1.NR.2.2
Use pictures, drawings, and equations to develop strategies for addition and subtraction within 20 by exploring strings of related problems.
- 1.NR.2
Explain the relationship between addition and subtraction and apply the properties of operations to solve real-life addition and subtraction problems within 20.
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