3rd Grade · Measurement & Data
3.MD.C.7: Find the area of a rectangle by multiplying its length and width
3.MD.C.7 is a 3rd grade Common Core math standard in Measurement & Data. Here’s what it really covers, and how you can help your students learn it.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
The standard
Relate area to the operations of multiplication and addition. a. Find the area of a rectangle with whole-number side lengths by tiling it, and show that the area is the same as would be found by multiplying the side lengths. b. Multiply side lengths to find areas of rectangles with whole-number side lengths in the context of solving real world and mathematical problems, and represent whole-number products as rectangular areas in mathematical reasoning. c. Use tiling to show in a concrete case that the area of a rectangle with whole-number side lengths a and b + c is the sum of a × b and a × c. Use area models to represent the distributive property in mathematical reasoning. d. Recognize area as additive. Find areas of rectilinear figures by decomposing them into non-overlapping rectangles and adding the areas of the non-overlapping parts, applying this technique to solve real world problems.
In plain words
Find the area of a rectangle by multiplying its length and width.
Sample questions from student practice
These questions from Bobby's Math Club are the kinds of questions your students will see. You can try answering them to see what a student might see.
Question 1 of 3
A rectangle is made of square tiles. There are 3 rows with 2 tiles in each row. What is the area of the rectangle?
- 6 square units
- 10 square units
- 5 square units
Where students can get stuck
- Adding the length and width instead of multiplying, so a 6 by 4 rectangle gets an area of 10 instead of 24.
- Counting an overlapping section twice when splitting an L-shape, or using the wrong side length for one piece.
- Multiplying every side length on an L-shaped figure together, getting a huge number instead of adding two areas.
Effective teaching strategies
- Build a 4 by 6 rectangle from tiles, then show it as 4 rows of 6, so students connect counting squares to multiplying.
- Split an L-shaped figure into two rectangles, find each area, and add, then try a different split to check the total.
- Ask students to compare the sum and the product of 6 and 4, and say which one counts the squares inside the rectangle.
Units that teach this standard
Find where 3.MD.C.7 lands in the program you teach. Each unit has a guide written for families. Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence.
Bridges in Mathematics
enVision Mathematics
Eureka Math
Eureka Math²
i-Ready Classroom Mathematics
Illustrative Mathematics
Math Expressions
Reveal Math
Zearn Math
Don’t see your curriculum? Contact Bobby and we’ll see if we can help!
Share it with families
Families can read Finding the area of a rectangle for a plain-language look at this skill, with three questions to try together and ideas for helping at home.
Help every student practice measurement and data at home
In Bobby's Math Club, students practice 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 for every family.
See how it works for teachers
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.