Illustrative Mathematics Grade 5, Unit 4: Wrapping Up Addition and Subtraction with Fractions
In this unit, your child finishes adding and subtracting fractions with unlike denominators, including mixed numbers. They find common denominators, solve story problems, and use line plots of measurements like 1/8 and 1/4 inch to answer questions about the data. Coming after multiplying and dividing fractions, it ties the fraction work together before place value patterns and decimal operations.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 4?
- Adding and subtracting fractions and mixed numbers with unlike denominators, like 2 3/4 + 1 5/8 = 4 3/8. Learn more: Adding and subtracting fractions like 2/3 + 1/4
- Solving story problems with fractions of the same whole, and checking answers with estimates and benchmark fractions. Learn more: Story problems that add and subtract fractions
- Making line plots of measurements in 1/2, 1/4, and 1/8 inch, and adding or subtracting fractions to answer questions about the data. Learn more: Measurement charts with halves, quarters, and eighths
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
- Measure the heights of a few toys or books to the nearest 1/8 inch. Make a line plot together and ask your child for the total of the three shortest.
- Add two lengths of ribbon or string, like 2 3/4 feet and 1 5/8 feet. Ask your child to estimate about 4 1/2 feet first, then find 4 3/8 feet.
- Ask how much more milk a recipe needs: you have 1/3 cup and need 3/4 cup. Let your child find 5/12 cup and explain the common denominator.
Where kids can get stuck
- Changing only the denominator, so 3/4 becomes 3/8 instead of 6/8 when adding it to 5/8.
- Accepting an impossible sum, like 1/3 + 1/2 = 2/5, without seeing it must be more than 1/2.
- Spacing 1/8, 1/4, and 1/2 evenly on a line plot, as if they were 1, 2, and 3.
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.
- mixed number
- A whole number and a fraction together, like 2 1/2.
- benchmark fraction
- An easy fraction like 0, 1/2, or 1 used to estimate or compare.
- line plot
- A number line with X marks that shows how often each measurement appears.
- data
- Numbers gathered by measuring, counting, or asking.
- eighth
- One of 8 equal parts of a whole, written 1/8.
Ready to build your child’s confidence with fractions and line plots?
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.
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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 Illustrative Mathematics Grade 5 Unit 4 cover?
Illustrative Mathematics Grade 5 Unit 4 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.