CCSS.Math.Content.5.NF.A.1
The standard
Add and subtract fractions with unlike denominators (including mixed numbers) by replacing given fractions with equivalent fractions in such a way as to produce an equivalent sum or difference of fractions with like denominators.
Common Core State Standards for Mathematics · Number and Operations—Fractions
What this standard means
Students need to add and subtract fractions and mixed numbers when the denominators are different. They should find a common denominator, rename each fraction as an equivalent fraction, then add or subtract the numerators. They also need to explain why the renamed fractions have the same value as the originals.
Mastery looks like choosing a workable common denominator, keeping the whole number parts straight, and simplifying only after the operation if needed. Students often get stuck by adding denominators, changing only one fraction, or losing track when regrouping mixed numbers during subtraction.
Ways to teach it
- Use fraction strips to build 1/2 plus 1/3, trade them for sixths, then record the matching equation.
- Ask students to explain in writing why 3/4 minus 1/6 becomes 9/12 minus 2/12 before subtracting.
- Give three problems on an exit ticket: one sum, one difference, and one mixed number subtraction with regrouping.
- Use a recipe card and ask students to find the total flour needed for 2/3 cup plus 3/4 cup.
Plan a lesson for CCSS.Math.Content.5.NF.A.1
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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.
- CCSS.Math.Content.4.NF.B.3c
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 operation...