1. Find Area
Mrs. Planavsky
4th Grade

2. Measure and find the area of plane figures
Today’s Objective
Measure and find the area of plane figures

3. Why is it important?
You can use multiplication to find the amount of carpet or tile needed for a room.

4. Quick Review
4 x 9 36
5 x 6 30
5 x 5 25
4 x 3 12

5. Learn
Mr. Jones is putting 1-square-foot tiles on the shower wall for his bathroom. Estimate the number of tiles he needs to cover the wall.

6. Think How many squares are in each row? How many rows are needed?
3 x 3 = 9

7. There are two ways to find the area of a plane.
You can count the square units to find the area.
You can use a formula.

8. You can count square units to find the area.
Draw a rectangle 7 cm long and 5 cm wide.

9. Count the number of squares.

10. You can count square units to find the area.
Draw a rectangle 7 cm long and 5 cm wide.

11. You can also use a formula.
The formula for the area of a rectangle is
Area = length x width or A = l x w.

12. Then…
Record your answer in square units.
A = 35 cm squared

13. Use the formula to find the area.
A = l x w
A = 7 x 5
A = 35 cm
7 cm
5 cm
5 cm
7 cm

14. You can divide figures into parts to find the area of plane as well.
What is the area of this figure?
It is easier to find the area of some figures by dividing them into rectangles first.

15. Divide the figure into two rectangles.

16. Find the area of each shaded part.

17. Question…
Why can you use the formula A = S x S for the area of a square?
The length and width of a square are equal, so you can multiply side times side to find the area of a square.

18. Add the areas together to find the total area of the figure.
= 39
So, the total area is 39 sq cm.

19. Describe situations in which someone might need to find area.
Buying tile
Carpet for the floor
Wallpaper for a wall
Gallons of paint for a wall or ceiling

20. Math is so fun!