Illustrative Mathematics Grade 4, Unit 5: Multiplicative Comparison and Measurement
In this unit, your child compares amounts by multiplying, like "4 times as tall," and solves comparison story problems. They use these ideas to convert measurements, such as feet to inches and kilograms to grams, solve measurement problems, and find the area and perimeter of rectangles. It follows the decimals unit and leads into multiplying and dividing multi-digit numbers.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 5?
- Describing comparisons with "times as many" and writing them as equations, like 32 = 4 × 8. Learn more: Reading multiplication as "times as many"
- Solving comparison problems with diagrams, including ones where the larger amount is known and the smaller is unknown. Learn more: Story problems about "times as many"
- Solving multi-step measurement problems, like finding the total length of ribbon needed for several projects. Learn more: Multi-step story problems and leftovers
- Converting larger units to smaller ones within a system, like 3 kilograms to 3,000 grams, by multiplying. Learn more: Converting feet to inches and kilograms to grams
- Solving story problems about lengths, weights, liquid volumes, time, and money, sometimes changing units first. Learn more: Story problems about distance, time, and money
- Finding the area and perimeter of rectangles, and a missing side, in problems about rooms, gardens, and rugs. Learn more: Using area and perimeter to solve real problems
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
A man is 6 feet tall. A giraffe is 3 times as tall as the man. Which equation finds g, the giraffe's height in feet?
- g = 3 × 6
- 6 = 3 × g
- g = 3 + 6
How you can help
- Measure a family member and a stuffed animal with a tape measure, like 60 inches and 12 inches. Ask how many times as tall the person is, and say it as 60 = 5 × 12.
- Read the weight on a bag of rice, like 2 kilograms, and ask your child how many grams it holds. Then ask how many 250-gram portions it would make.
- Measure a rug or bath mat. Ask your child for the trim around it and the space it covers, and how they'd find a missing side if they knew the area.
Where kids can get stuck
- Getting a comparison backwards, so 8 seems to be 4 times as many as 32.
- Adding instead of multiplying, so "3 times as heavy as 6 kilograms" becomes 9 kilograms.
- Converting 5 kilograms to 50 grams, assuming every metric step is ten.
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
- times as many
- A way to compare two amounts by saying how many copies of one make the other.
- multiplicative comparison
- Comparing two amounts by multiplying, as in "15 is 3 times as many as 5."
- equation
- A number sentence with an equal sign, showing both sides have the same value.
- convert
- To change a measurement into a different unit, like 3 feet into 36 inches.
- kilogram
- A metric unit of mass equal to 1,000 grams.
- gram
- A small metric unit of mass, about the mass of a paper clip.
- area
- The space inside a flat shape, measured in square units.
- perimeter
- The distance all the way around a flat shape.
Want to help your child master multiplicative comparison?
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 4 Unit 5 cover?
Illustrative Mathematics Grade 4 Unit 5 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
- 4.OA.A.1: Understand "times as many": 35 is 5 times as many as 7.
- 4.OA.A.2: Solve "times as many" word problems by multiplying or dividing.
- 4.OA.A.3: Solve word problems with several steps, including ones with remainders.
- 4.MD.A.1: Change larger units into smaller ones, like 4 feet = 48 inches.
- 4.MD.A.2: Solve word problems about distance, time, liquids, weight, and money.
- 4.MD.A.3: Solve problems with the area and perimeter of rectangles.
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.