Eureka Math Grade 5, Module 3: Addition and Subtraction of Fractions
In this unit, your child adds and subtracts fractions with unlike denominators. They find a common unit, so 2/5 + 1/3 becomes 6/15 + 5/15, work with mixed numbers, and check answers against benchmarks like 1/2 and 1. After a unit of whole number and decimal operations, fractions get full attention before the next unit multiplies and divides fractions and decimals.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Module 3?
- Finding a common unit to add and subtract, so 2/5 + 1/3 becomes 6/15 + 5/15 = 11/15, including with mixed numbers. Learn more: Adding and subtracting fractions like 2/3 + 1/4
- Solving word problems with fractions and checking whether an answer is sensible, like knowing 2/5 + 1/2 must be more than 1/2. Learn more: Story problems that add and subtract fractions
Sample questions to try together
These are real questions from our practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
Question 1 of 3
Which common denominator could you use to add 3/4 and 5/6?
- 10
- 12
- 6
How you can help
- Use a tape measure together to add lengths like 2 1/2 feet and 1 3/4 feet. Ask your child to find the total, 4 1/4 feet, and explain how they renamed the fractions.
- Cut one paper strip into fifths and another into thirds. Ask your child how to cut both so the pieces match, then show that 2/5 − 1/3 is 1/15.
- Ask a sense check before any work: Lily walked 2/3 mile and Sam walked 1/4 mile. Who walked farther, and by about how much? Then find the exact difference, 5/12 mile.
Where kids can get stuck
- Adding tops and bottoms, so 2/5 + 1/3 becomes 3/8 instead of 11/15.
- Renaming only one fraction, so 2/5 + 1/3 becomes 6/15 + 1/3 with mismatched pieces.
- Mixing up different wholes, treating half of a small pizza and half of a large pizza as the same amount.
Practice makes perfect
Bobby's Math Club has practice problems that adapt to your child’s level, each with a detailed explanation and an easy-to-follow video, so your child can build confidence in these skills one step at a time.
Words your child will hear
- common denominator
- The same bottom number shared by two fractions, so their parts are the same size.
- equivalent fractions
- Fractions that name the same amount, like 1/2 and 3/6.
- numerator
- The top number of a fraction, which counts how many parts you have.
- denominator
- The bottom number of a fraction, which tells how many equal parts make a whole.
- mixed number
- A number written as a whole number plus a fraction, like 3 3/4.
- benchmark fraction
- An easy fraction like 0, 1/2, or 1 used to estimate or compare.
- whole
- The full amount that a fraction is a part of.
Want to help your child master fraction addition and subtraction?
In Bobby's Math Club, your child practices these skills at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free.
Join the club
Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.
Which math standards does Eureka Math Grade 5 Module 3 cover?
Eureka Math Grade 5 Module 3 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
For teachers: Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence. Learn how Bobby's Math Club can help your students grow.