Maryland Math 5.NOS.C.8.c
The Standard
- 5.NOS.C.8
- Add and subtract fractions with unlike denominators.
Use equivalent fractions to produce an equivalent sum or difference of fractions with like denominators (e.g. 2/3 + 5/4 = 8/12 + 15/12 = 23/12. In general, a/b + c/d = (ad + bc)/bd).
Maryland College and Career Ready Standards for Mathematics (2025) · USE EQUIVALENT FRACTIONS AS A STRATEGY TO ADD AND SUBTRACT FRACTIONS.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students rewrite fractions with different denominators as equivalent fractions with a shared denominator. They add or subtract the numerators and keep the shared denominator.
What Mastery Looks Like
- For 2/3 + 1/4, a student writes 8/12 + 3/12 = 11/12 and explains why both fractions kept their value. For 3/4 - 1/6, they get 7/12 and check that it is less than 3/4.
Common Misconceptions
- Students may add or subtract the denominators along with the numerators. Some change the denominator without changing the numerator, or think the shared denominator must be the product of the original denominators.
How to Assess It
- Exit ticket: Solve 3/4 - 1/6 by rewriting both fractions with the same denominator. Show how you made each equivalent fraction.
Lesson moves
Ways to Teach It
Give students half and third fraction strips; have them cover each strip with sixths, then show 1/2 + 1/3 = 5/6.
Ask partners why 2/3 + 1/4 is not 3/7; have them sketch twelfths and write a two-sentence reply.
Run a card match: students pair 3/4 - 1/6 with 9/12 - 2/12 and 7/12, then explain the match.
Put a recipe using 3/4 cup milk and 2/3 cup water on the board; students find the total liquid in cups.
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Related Standards
- 4.NOS.E.11
Apply understanding of a fraction c/d with d > 1 as a sum of unit fractions (1/d) to decompose a fraction (including fractions greater than 1) into a sum of fra...
- 5.NOS.D.11
Apply and extend previous understandings of multiplication to multiply a whole number by a fraction (c/d × b).
- 3.NOS.F.13.b
Identify and generate equivalent fractions, (e.g., 1/2 = 2/4, 4/6 = 2/3.) and explain why the fractions are equivalent using concrete materials, drawings, numbe...
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