i-Ready Classroom Mathematics Grade 3, Unit 4: Area and Perimeter
In this unit, your child measures area, the flat space a shape covers, and perimeter, the distance around it. They tile and count squares, multiply side lengths, split shapes into rectangles, and add side lengths to find perimeter. Multiplication facts from earlier help with area, and the equal-parts work here leads into fractions in the next unit.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 4?
- Covering shapes with unit squares, no gaps or overlaps, to find how much space each one takes up. Learn more: Area: how much flat space a shape covers
- Measuring area by counting square units, including square feet and square meters for big spaces like a room. Learn more: Finding area by counting squares
- Using multiplication for a rectangle's area and splitting other shapes into rectangles, such as a 5 by 2 piece plus a 3 by 3 piece. Learn more: Finding the area of a rectangle
- Adding side lengths to find perimeter, working out a missing side, and comparing shapes with the same area but different perimeters. Learn more: Perimeter: the distance around a shape
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
You want to cover a rectangular garden with new grass. Which measurement tells you how much grass you need?
- Perimeter
- Length
- Area
How you can help
- Count the tiles in a section of floor row by row and ask your child how a multiplication fact gives the total faster.
- Draw a room shaped like an L on paper, label the sides, and ask your child to find its area and the distance around it.
- Wrap a piece of string around the edge of a book cover, then lay it flat and measure it with a ruler to find the perimeter.
Where kids can get stuck
- Counting grid lines instead of squares, so a shape 4 squares wide is counted as 5.
- Multiplying length by width when asked for perimeter, so a 6 by 2 rectangle gets 12 instead of 16.
- Using the wrong side length for one part of an L-shape after splitting it.
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
- area
- How much flat space a shape covers.
- perimeter
- How far it is around the edge of a flat shape.
- unit square
- A square with sides 1 unit long; it has an area of 1 square unit.
- square unit
- A square used to measure area, like a square inch or square foot.
- square foot
- A square 1 foot long on each side.
- side length
- The measurement of one side of a shape.
- rectilinear figure
- A shape built from rectangles, with every corner a square corner.
- length
- How long something is from end to end.
- width
- How far across something is from side to side.
Ready to build your child’s confidence with finding area and perimeter?
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 i-Ready Classroom Mathematics Grade 3 Unit 4 cover?
i-Ready Classroom Mathematics Grade 3 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.