NY Next Generation Math NY-4.NF.3.b
The Standard
Decompose a fraction into a sum of fractions with the same denominator in more than one way, recording each decomposition by an equation. Justify decompositions.
New York State Next Generation Mathematics Learning Standards
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students break a fraction into sums of fractions with the same denominator in several ways. They record each decomposition as an equation and justify it with a model or fraction reasoning.
What Mastery Looks Like
- The student writes 5/8 as 1/8 + 4/8 and as 2/8 + 3/8. The student uses a visual model to show that each sum names the same whole amount.
Common Misconceptions
- Students may change denominators while decomposing or create addends that do not total the original numerator. They may write equations without showing why the amounts match.
How to Assess It
- Ask students to decompose 7/10 in two different ways with like denominators and justify both equations with one model.
Lesson moves
Ways to Teach It
Cut a fraction strip into unit-fraction parts and regroup the parts to record several same-denominator sums.
Ask students how they can know two decompositions of 5/6 have the same value without recalculating the whole.
Play fraction-decomposition challenge by drawing a target fraction and creating distinct valid equations.
Split a measured amount into several same-unit portions and record different combinations that preserve the total.
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Printable NY-4.NF.3.b Worksheet
A ready-to-print activity worksheet aligned to NY-4.NF.3.b, with an answer key for the teacher on its own page. No account needed.
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