Maryland Math 4.NOS.E.12.c
The Standard
- 4.NOS.E.12
- Apply and extend previous understanding of addition and subtraction of whole numbers to add and subtract fractions with like denominators.
Apply and extend whole number addition and subtraction strategies (e.g. counting on, making a whole, partial sums, compensation, properties of operations, the inverse relationship between addition and subtraction) to add and subtract fractions.
Maryland College and Career Ready Standards for Mathematics (2025) · BUILD FRACTIONS FROM UNIT FRACTIONS BY APPLYING AND EXTENDING PREVIOUS UNDERSTANDINGS OF OPERATIONS ON WHOLE NUMBERS.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students add and subtract fractions by counting on, making a whole, or using addition to check subtraction. They keep track of the size of each piece when an answer crosses one whole.
What Mastery Looks Like
- A student can find 7/8 + 5/8 by making 1 whole, then adding the remaining 4/8. They can check the answer by subtracting 5/8 from 1 4/8.
Common Misconceptions
- Students may add denominators, turning 2/8 + 3/8 into 5/16. When subtracting 3/8 from 1 1/8, they may forget to rename the whole as 8/8.
How to Assess It
- Give this exit ticket: Find 7/8 + 5/8 by making a whole. Then check your answer with subtraction.
Lesson moves
Ways to Teach It
Give pairs eighths fraction strips to build 7/8 + 5/8, trade eight eighths for a whole, and record the sum.
Ask students to explain in writing why renaming 1 1/8 as 9/8 helps them subtract 3/8.
Have partners draw two eighths fraction cards, add them by counting on, and check each sum with subtraction.
Show a recipe that needs 1 1/4 cups of oats and has 3/4 cup; ask how much more oats it needs.
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Printable 4.NOS.E.12.c Worksheet
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Related Standards
- 1.NOS.E.13.b
Use counting strategies, properties of operations, and/or the inverse relationship between addition and subtraction to subtract.
- 5.NOS.D.13.b
Apply and extend whole number multiplication strategies (e.g. area model, partial products).
- 4.NOS.E.12
Apply and extend previous understanding of addition and subtraction of whole numbers to add and subtract fractions with like denominators.
- 5.NOS.C.8.b
Apply and extend whole number addition and subtraction strategies (e.g. counting on, making a whole, partial sums, compensation, properties of operations, the i...
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