MathIsimple

Geometry: Area & Perimeter

Learn to calculate the space inside and distance around shapes!

3rd Grade
Geometry
🎮 Interactive Activity: Area & Perimeter
4 units
3 units
Area = length × width
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1. Perimeter

📏 Distance Around

Perimeter is the total distance around a shape. Think of it as walking around the edge of a shape - how far would you walk? Add all the sides together!

Rectangle: P = 2 × (length + width)

Square: P = 4 × side

💡 Why 2 × (length + width)? A rectangle has 2 lengths and 2 widths. So we add length + width, then multiply by 2!

📝 Examples

Example 1: Rectangle: 6 cm × 4 cm

P = 2 × (6 + 4) = 2 × 10 = 20 cm

Example 2: Square with side 5 m

P = 4 × 5 = 20 m

Example 3: Rectangle: 8 ft × 3 ft

P = 2 × (8 + 3) = 2 × 11 = 22 ft

🏠 Real-World Applications

Perimeter is used for:

  • Fencing a yard (how much fence do you need?)
  • Putting a border around a picture
  • Measuring the edge of a table
  • Finding how much ribbon you need to wrap a box
🔷 Irregular Shapes

For shapes that aren't rectangles or squares, just add up all the side lengths! For example, a triangle with sides 3 cm, 4 cm, and 5 cm has perimeter 3 + 4 + 5 = 12 cm.

2. Area
3. Different Shapes
4. Area vs Perimeter
5. Real-World Applications

Practice Time!

Practice Quiz
10
Questions
0
Correct
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Score
1
What is the area of a rectangle 5 units by 4 units?
2
What is the perimeter of a square with sides of 6 cm?
3
A rectangle is 8 m long and 3 m wide. What is its perimeter?
4
What unit is used for area?
5
A garden is 10 ft by 7 ft. What is its area?
6
What is the perimeter of a rectangle 9 × 5?
7
If a square has area 25 sq cm, what is each side?
8
Which measures the distance around a shape?
9
A room is 12 ft × 10 ft. How much carpet is needed?
10
How many sides does a rectangle have?