CCSS.Math.Content.4.NF.B.3c
The Standard
Add and subtract mixed numbers with like denominators, e.g., by replacing each mixed number with an equivalent fraction, and/or by using properties of operations and the relationship between addition and subtraction.
Common Core State Standards for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students add and subtract mixed numbers whose fractional parts share a denominator. They choose a method, such as regrouping a whole or converting to equivalent fractions, and justify the result.
What Mastery Looks Like
- Students accurately add and subtract mixed numbers, including problems that require composing or decomposing a whole. They can use equivalent fractions or separate whole and fractional parts, explain their steps, and check subtraction with addition.
Common Misconceptions
- Students may add or subtract denominators instead of keeping the common denominator. They may work with whole and fractional parts separately but forget to regroup when the first fraction is smaller. Some convert mixed numbers incorrectly by omitting the original numerator.
How to Assess It
- Exit ticket: Solve 3 2/5 minus 1 4/5. Show regrouping or conversion to equivalent fractions, then check the answer with addition.
Lesson moves
Ways to Teach It
Use fraction strips to model 2 3/4 minus 1 1/4, then repeat with a problem that requires trading one whole.
Ask students to compare two solutions for 2 3/8 plus 1 7/8 and explain which method they find clearer.
Play a matching game with cards showing mixed-number expressions, equivalent fraction forms, and simplified answers.
Have students combine or compare recipe amounts with like denominators, such as 1 3/4 cups and 2 1/4 cups.
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Printable 4.NF.B.3c Worksheet
A ready-to-print activity worksheet aligned to CCSS.Math.Content.4.NF.B.3c, with an answer key for the teacher on its own page. No account needed.
PDF, US Letter, prints cleanly in black and white.
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Where This Standard Sits
Before This Standard
If students are struggling here, check these first.
- CCSS.Math.Content.4.NF.B.3b
Decomposing like-denominator fractions supports regrouping mixed numbers and trading wholes for fractional parts when adding or subtracting.
- CCSS.Math.Content.4.NF.B.3a
Mixed-number operations require combining or separating the fractional parts as same-size parts of the same whole.
- CCSS.Math.Content.3.NF.A.3c
Converting whole-number parts into denominator-sized fractions supports rewriting and regrouping mixed numbers with like denominators.
What This Unlocks
Mastery here sets students up for these next.
Keep exploring
Related Standards
- CCSS.Math.Content.5.NF.A.2
Solve word problems involving addition and subtraction of fractions referring to the same whole, including cases of unlike denominators, e.g., by using visual f...
- CCSS.Math.Content.4.NF.B.3d
Solve word problems involving addition and subtraction of fractions referring to the same whole and having like denominators, e.g., by using visual fraction mod...
- CCSS.Math.Content.5.NF.A
Use equivalent fractions as a strategy to add and subtract fractions.
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