## Key Concepts

- Square units (cm2 and in2)
- Square Units ( m and ft)

## What is a Square Unit?

A square unit is a metric unit used to measure an area.

For instance, the area of the rectangle is measured in square units using unit squares.

### Unit Square:

A unit square is a square with sides measuring 1 unit, while a square unit is a unit of measurement.

Examples of square units are,

Metric Units – Square millimetre (mm^{2}), square centimetre (cm^{2}), square metre (m^{2}) and square kilometre (km^{2})

Customary Units – Square inches (in^{2}), square foot (ft^{2}), square yard (yd^{2}), square mile (mi^{2})

**Facts:**

- 1 square metre (m
^{2}) is larger than 1 square centimetre (cm^{2}) - 1 square foot (ft
^{2}) is larger than 1 square inch (in^{2})

### Square Centimetre (cm^{2}):

The square centimetre (cm^{2}) is a metric unit of measure for the area.

A square of sides 1 cm (shown below) has an area of 1 square centimetre, also written as 1 cm^{2}.

**Example:**

What is the area of the shaded figure below?

The figure is made up of seven 1 cm squares.

The area of each 1 cm square is 1 cm^{2}.

So, the area of the shaded figure is 7 cm^{2}.

### Square Inch (in^{2}):

A square inch is a unit of area equal to the area of a square with sides of one inch.

**Example:**

Find the area of the rectangle below.

The width is 10 inches and the height is 6 inches.

Multiply these two numbers together.

10 × 6 = 60

∴The area of the rectangle is 60 square inches (in^{2}).

**19.3 Square Units – Square Metre and Square Foot (m**^{2}** and ft**^{2}**)**

^{2}

^{2}

A square metre is defined as the basic unit of length in the metric unit to measure the area.

A square of sides 1 m (shown below) has an area of 1 square metre, also written as 1

**Example:**

How many squares does this green rectangle cover?

Each square in the grid above is 1 square metre.

Then the area of the green rectangle is 6 square metres (m^{2}).

**Square Foot (ft**^{2}**):**

^{2}

A square foot is an area whose measurement is 1 foot by 1-foot square. It is abbreviated as sq. ft or ft^{2}.

Square feet are smaller than square metres.

1 m^{2} can fit over 10 ft².

**Example:**

What is the area of the square below?

The length of one side is 4 feet.

Multiply by itself

4 ft × 4 ft = 16 square feet

∴The area of the square is 16 square feet or 16 ft^{2}.

## Exercise

1. Find the area of a rectangle with a base of 4 inches and a width of 5 inches

2. A swimming pool is 8 meters wide and 9 meters long. What is the area of the pool in square meters?

3. Find the area in unit squares.

4. What is the area of a rectangle that has a length of 7 feet and a width of 4 feet?

5. Draw the figure which has an area of 16 square units.

6. Sam is setting up 3 tables for a bake sale. If each table has a length of 2 meters and a width of 2 meters, what is the total area of all three tables?

7. What is the formula to find the area of a rectangle?

8. If the length is 6 feet and the width is 2 feet, what is the area of this rectangle?

9. Nathan is measuring a square tile. One side is 3 inches. What is the area of the square tile in square inches?

10. Wade wants to put sod (grass) in his backyard. The length of the yard is 12 feet and the width is 3 feet. How much sod will Wade need to cover the area of his backyard?

### What Have We Learned:

- Use square units to find the area of plane figures made of squares and half squares
- Compare areas of plane figures and make plane figures of the same area
- Use square centimetres and square inches to find and compare the area of the figures
- Use square meters and square feet to find and compare the area of plane figures
- Find an area in square units such as square centimetres, square inches, square meters, and square feet

**Concept Map:**

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