CCSS.Math.Content.4.NF.B.3
The standard
Understand a fraction a/b with a > 1 as a sum of fractions 1/b.
Common Core State Standards for Mathematics · Number and Operations—Fractions
What this standard means
Students need to see fractions greater than one unit fraction as repeated pieces of the same size. For example, 3/8 means 1/8 + 1/8 + 1/8. They should connect fraction notation, pictures, number lines, and addition equations.
Mastery looks like building and explaining fractions from unit fractions without relying only on shaded circles. Students can write 5/6 as five sixths, show it on a number line, and match it to an equation. Common trouble spots are mixing denominators, counting pieces without checking equal size, and treating the numerator and denominator as separate whole numbers.
Ways to teach it
- Have students use fraction strips to build 4/5, 7/8, and 3/6, then write each as a unit fraction sum.
- Ask students to explain in writing why 5/7 is not 1/5 + 1/7.
- Show a shaded model or number line point and have students write the fraction and its unit fraction addition equation.
- Use a recipe with 1/4 cup scoops and ask how many scoops make 3/4 cup, 5/4 cups, and 6/4 cups.
Plan a lesson for CCSS.Math.Content.4.NF.B.3
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Related standards
- CCSS.Math.Content.3.NF.A.1
Understand a fraction 1/b as the quantity formed by 1 part when a whole is partitioned into b equal parts; understand a fraction a/b as the quantity formed by a...
- CCSS.Math.Content.4.NF.B.4a
Understand a fraction a/b as a multiple of 1/b.
- CCSS.Math.Content.4.NF.A.1
Explain why a fraction a/b is equivalent to a fraction (n × a)/(n × b) by using visual fraction models, with attention to how the number and size of the parts d...
- CCSS.Math.Content.4.NF.B.4b
Understand a multiple of a/b as a multiple of 1/b, and use this understanding to multiply a fraction by a whole number.