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### Course: 3rd grade (Eureka Math/EngageNY)>Unit 4

Lesson 2: Topic B: Concepts of area measurement

# Area of rectangles review

Review the basics of area of rectangles and try some practice problems.

## What is area?

Area is the space inside of a two-dimensional shape. We can also think of area as the amount of space a shape covers.
For example, the rectangle below has an area of $12$ square units because it covers $12$ square units.

## Area of a rectangle formula

To find the area of a rectangle, we multiply the length of the rectangle by the width of the rectangle.
$\text{Area of rectangle}=\text{length}×\text{width}$
Want to know why this formula works? Check out this video.

### Example 1:

$\text{Area}=\text{length}×\text{width}$
$\phantom{\text{Area}}=6×2$

### Example 2:

$\text{Area}=\text{length}×\text{width}$
$\phantom{\text{Area}}=7×4$

### Practice set 1: Multiply to find area

Problem 1A
What is the area of the rectangle?
square units

Want to try some more area of rectangle problems? Check out this exercise:
Area of rectangles

### Practice set 2: Count square units to find area

Problem 2A
What is the area of the shape? Each square in the grid is a $1×1$ unit square.
square units

### Practice set 3: Challenge items

Problem 3A
This cat and bird picture has an area of $56$ square centimeters. The height of the picture is $7$ centimeters.
What is the width of the picture?
centimeters

## Want to join the conversation?

• How do you figure out square feet? I need to calculate the area of a back splash so i can purchase wall tiles.
• for tiles times the length by the width and you get the area
• If a shape is uneven, how can we work out the area?
• Try to break the shape into simpler shapes - ones that have areas that are easy to calculate. Calculate the area of each smaller shape, then add them all together to get the area of the whole shape.
(This is what they did up above when they had us count squares to figure out the area of the big shape.)

Each square is 1x1, so the area of each square is one.
(First step: calculating the area of the smaller shapes.)

Then when we counted all the squares, the total number of squares was also the area of the shape.
(Second step: add together all the areas of the smaller shapes.)

Hope this helps!
• how do you find area of a 3D shape? is it multiplying 2D shapes? why does time pass in different time zones? how does an earthquake cause a tsunami? also, force can move things right? how can a smaller amount of force move a big object?
• time passes in different time zones cause of the way the earth is facing the sun
• what if you reverse the numbers of the area would the answers still be the same?🤔
• It would! For a rectangle, it doesn't really matter which side is length and which side is width. Because the order in which you multiply two numbers doesn't matter, the area is the same both ways. You can think of just turning a rectangle from the skinny side being horizontal to it being vertical. Nothing changes about the amount of space the rectangle takes up, so its area is the same :)
• this is a good practice but a bit tricky