Multiply Side Lengths to Find Rectangle Area

Students will use multiplication of whole-number side lengths to efficiently find the area of rectangles without tiling. They will apply this skill in real-world contexts such as finding the area of a room, a garden, or a tile floor.

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Real questions from this skill, graded here. No account, and nothing is saved.

Grade 3 · Area and Multiplication · question 1 of 3

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12 rungs. A star at the top.

A garden is 6 feet long and 4 feet wide. Which shows how to find the area?

6 + 6 + 4 + 4

6 − 4

6 × 4

6 + 4

How it is taught

0:00 of 3:06

Area of a rectangle is length times width.

Area is counted in square units.

Read it: Count inside, walk around

You have a frame, three cells by four. Twelve cells sit filled inside. Then walk all the way around.

Count the filled cells inside: twelve.
Walk the four sides: four, three, four, three.
Say twelve inside and fourteen around the edge.

Counting every filled cell from one works, but it is slow, and mixing in the edge cells double-counts corners.

The twelve inside cover the floor, while the fourteen round are only the fence.

Three rows of four make twelve inside without walking the edge at all.

Count the cells inside, then walk all the way around: two measurements of one shape.

Counting the walk around and saying fourteen cells fill the frame.

Fourteen is the edge; the fill is twelve cells inside.

A rectangle is 3 squares by 2. How many squares cover it? — 6. 3 rows of 2 squares: skip-count the rows — 2, 4, 6.

5 ft × 3 ft

Maya is planting a garden. It's five feet long and three feet wide. What's the area?

Here's her garden — five feet on one side, three feet on the other.

Grade 3 · Finding the area of a rectangular garden

Here's the garden covered with one-foot square tiles.

Each row has five squares — the same as the length.

And there are three rows — the same as the width.

Instead of counting tiles one by one, we just multiply the side lengths: five times three.

Five times three is fifteen.

Because the tiles are squares, the area is fifteen square feet.

Multiply the side lengths to find the area. Maya's garden is fifteen square feet!

Now you try. Multiply the side lengths to find the area. Type the area.

What you see

While they climb, your page writes one true line to ask about tonight, and a short note each Sunday.

MayaGrade 3 · Mathematics

Did you know?

A chessboard has 64 squares — share them out between the 8 rows and each row holds exactly 8.

Today’s goal: 1 star — one skill mastered, every rung of its ladder climbed
Climbing now: Divide within 100

An example student.

MayaGrade 3 · Mathematics

Maya earned 2 stars this week — Interpret multiplication as equal groups, which took 6 answers over 3 days before its star landed 3 days ago and Multiply by 6, 7, 8 and 9. Next up: Divide within 100.

An example week.

More of the library

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Standards

CCSS.3.MD.C.7

Relate area to the operations of multiplication and addition

CCSS.3.MD.C.7b

Multiply side lengths to find areas of rectangles with whole-number side lengths in the context of solving real-world and mathematical problems

Grade 3

Quoted from the Common Core State Standards.

Where this sits

Comes after

Find Area by Tiling and Multiplying Side Lengths

Leads to

What a star here means

A star here is the top of a twelve-rung ladder, in four blocks of equal length — three of facts and one of the skill used in a real question — where a right answer climbs one rung and a wrong one drops back to the start of the block, never below it. The star is kept for good. How we grade

All of Grade 3

This is one rung of 104 in Grade 3 mathematics, in the order they build on each other.

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