NY Next Generation Math NY-4.NF.3.c

Math4th GradeUnderstand a fraction a/b with a > 1 as a sum of fractions 1/b.

The Standard

Add and subtract mixed numbers with like denominators.

New York State Next Generation Mathematics Learning Standards

Teacher's field guide

What This Standard Means

What Students Need to Do

Students add and subtract mixed numbers that have like denominators. They may work with equivalent improper fractions or combine whole-number and fractional parts.

What Mastery Looks Like

The student finds 2 3/8 + 1 6/8 and renames 9/8 as 1 1/8 to get 4 1/8. The student handles needed regrouping in subtraction accurately.

Common Misconceptions

Students may add denominators or combine whole numbers but ignore fractional parts. They may regroup one whole as the wrong number of denominator-sized pieces.

How to Assess It

Ask students to solve 5 1/6 - 2 4/6 and show how one whole is renamed as 6/6.

Lesson moves

Ways to Teach It

  1. Combine and separate mixed-number fraction strips, exchanging one whole for denominator-sized pieces when needed.

  2. Ask students to explain why one whole becomes 8/8 when working with eighths.

  3. Play mixed-number method match with models, improper-fraction equations, and whole-plus-fraction strategies.

  4. Add or subtract mixed-number lengths with the same fractional unit for a craft plan.

Keep exploring

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