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
What this standard means
Students need to combine and compare mixed numbers that have the same denominator. They should know how to add or subtract the whole number parts and fraction parts, and when to rename a mixed number as an improper fraction. They also need to use subtraction as a check for addition.
Mastery looks like flexible thinking. A student can solve 2 3/5 + 1 4/5, explain whether to regroup, and show the answer in simplest mixed-number form. Common stuck points are subtracting a larger fraction part from a smaller one, forgetting to regroup 1 whole as fraction pieces, and adding denominators.
Ways to teach it
- Use fraction strips to build 2 3/4 minus 1 1/4, then record the matching equation and answer.
- Ask students to explain which method they prefer for 3 2/5 plus 1 4/5, mixed numbers or improper fractions, and why.
- Give three problems on an exit ticket, including one that needs regrouping, and ask students to show one check.
- Have students use a recipe card to add or subtract mixed-number amounts of cups with the same denominator.
Plan a lesson for CCSS.Math.Content.4.NF.B.3c
Generate a complete lesson plan aligned to this standard, with objectives, activities, and materials. Free, no account needed.
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.5.NF.A.1
Add and subtract fractions with unlike denominators (including mixed numbers) by replacing given fractions with equivalent fractions in such a way as to produce...
- 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.