Grade: Grade 3 Subject: Mathematics Unit: Area & Perimeter SAT: Geometry+Trigonometry ACT: Math

Finding Area

Have you ever wondered how much space is inside a shape? That's what area tells us! Learning to find area will help you with everything from covering a floor with tiles to wrapping a present.

What is Area?

Area is the Space Inside a Shape!

Imagine you're painting a rectangle on the wall. The area is how much paint you need to cover the whole inside of the shape. We measure area in square units.

🔲 Understanding Square Units

We measure area using small squares called square units. Each square unit is a square that is 1 unit long and 1 unit wide.

Common square units include:

Square inches - for small things like a sticky note

Square feet - for rooms and floors

Square meters - for bigger spaces

Remember: Area is always measured in square units because we're counting how many little squares fit inside the shape!

Counting Square Units

The easiest way to find area is to count the squares inside a shape!

Example 1: Small Rectangle
3 units wide, 2 units tall
Area = 6 square units
Example 2: Larger Rectangle
4 units wide, 3 units tall
Area = 12 square units
Example 3: Square
4 units wide, 4 units tall
Area = 16 square units

Try It Yourself: Count the Squares!

Click on squares to select them and count the area. See how many square units fit inside!

Click squares to count them

Squares selected: 0 square units

The Area Formula

Counting every square works, but there's a faster way! We can use multiplication.

The Magic Formula for Rectangles

Area = Length x Width

Just multiply how long it is by how wide it is!

🧮 Why Does This Work?

Think about a rectangle that is 4 units long and 3 units wide.

You could count: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 squares

OR

You could multiply: 4 x 3 = 12 square units

Same answer, but much faster!

📐 Using the Formula - Step by Step

Find the area of a rectangle that is 5 feet long and 3 feet wide.

  1. Write the formula: Area = Length x Width
  2. Put in the numbers: Area = 5 x 3
  3. Multiply: Area = 15
  4. Add the units: Area = 15 square feet

The area is 15 square feet!

Don't forget the units! If the length and width are in feet, the area is in square feet. If they're in inches, the area is in square inches.

Area Calculator

Enter the length and width to calculate the area automatically!

Enter the dimensions:

Length: units
Width: units
Area = 12 square units

Area in the Real World

Area is used everywhere! Here are some real-life examples:

🏠
Floor Space

How many tiles do you need to cover a floor? That's area!

🖼️
Picture Frames

How much glass goes in a frame? Find the area!

🌱
Garden Beds

How much dirt do you need? Calculate the area!

🎨
Painting Walls

How much paint do you need? Use area to find out!

📦
Wrapping Gifts

How much paper to wrap a box? That's area too!

🍕
Pizza Size

A bigger area means more pizza to eat!

Real World Problem:

Maria wants to put new carpet in her bedroom. The room is 10 feet long and 8 feet wide. How many square feet of carpet does she need?

Solution: Area = 10 x 8 = 80 square feet

Practice Problems

Now it's your turn! Use what you learned to find the area.

Problem 1

A rectangle is 6 units long and 4 units wide.
What is the area?

Problem 2

A square has sides that are 5 inches long.
What is the area?

Problem 3

A rug is 9 feet long and 7 feet wide.
What is the area?

Problem 4

A book cover is 8 inches long and 6 inches wide.
What is the area?

Problem 5

A playground is 12 meters long and 10 meters wide.
What is the area?

Challenge: Count and Calculate!

Count the squares in this shape, then check your answer!

How many square units?

Check Your Understanding

What does area measure?

What is the formula for the area of a rectangle?

If a rectangle is 3 feet by 4 feet, what unit is the area measured in?

What We Learned

🔲

Area

The space inside a shape, measured in square units.

🔢

Counting

You can count squares to find area.

x

Formula

Area = Length x Width is faster than counting!

🌍

Real World

Area helps with floors, gardens, painting, and more!

Great job! Now you know how to find the area of rectangles and squares. Keep practicing, and soon you'll be an area expert!

Next Steps

  • Practice finding areas of rectangles you see around you
  • Measure real objects and calculate their area
  • Remember: Area = Length x Width
  • When ready, move on to learn about Finding Perimeter!