Lesson 10: Perimeter and Area of Rectangles

Property

For a rectangle on a grid:

• Perimeter is the total number of unit lengths around the outside of the rectangle.
• Area is the total number of unit squares inside the rectangle.

Examples

• A rectangle with a length of $5$ units and a width of $3$ units on a grid has a perimeter of $2(5) + 2(3) = 16$ units and an area of $5 \times 3 = 15$ square units.
• A square with a side length of $4$ units on a grid has a perimeter of $4 \times 4 = 16$ units and an area of $4 \times 4 = 16$ square units.

Explanation

You can find the perimeter of a rectangle on a grid by counting the number of unit segments along its boundary. To find the area, you can count the number of unit squares that fill the inside of the rectangle. These counting methods provide a visual way to understand the formulas for perimeter and area, where length ($l$) and width ($w$) correspond to the number of units along the sides.