1. Finding Perimeter using a Grid
How can you find perimeter?

2. This is AREA! Finding the distance around a figure
Lesson Opening
For which of the following situations would it be helpful to know the distance around an area?
If you ran 3 laps around the outside of your house and you want to know how far you ran.
If you are putting up a fence around a garden and want to know how much fencing to buy.
If you want to put a wallpaper border around the top of your bedroom wall and you need to know how much wallpaper border to buy.
If you want to know how much tile you need for your kitchen floor.
Finding the distance around a figure
is finding the PERIMETER of a figure.
This is AREA!

3. Perimeter is the DISTANCE around a shape.

4. Perimeter is the DISTANCE around a shape.

6. To find the perimeter count the grid lines on all the sides.

7. To find the perimeter count the grid lines on all the sides.1 2 3
To find the perimeter count
the grid lines on all the sides.

8. To find the perimeter count the grid lines on all the sides.1 2 3 14 4 13 5 12 6 11 7 10 9 8
To find the perimeter count
the grid lines on all the sides.

9. This perimeter of this figure1 2 3 14 4 13 5 12 6 11 7 10 9 8
This perimeter of this figure
is 14 units.

11. To find the perimeter count the grid lines on all the sides.

12. To find the perimeter count the grid lines on all the sides.1 2 3 4 5 6 7 8 9
To find the perimeter count
the grid lines on all the sides.

13. To find the perimeter count the grid lines on all the sides.1 2 3 4 5 6 7 8 9
9 units
To find the perimeter count
the grid lines on all the sides.

14. 1 2 3 4 5 6 7 8 9
9 units
3 units
8 units
3 units
5 units
6 units

15. 9 + 3 + 3 + 5 + 6 + 8 = 34 units 9 units 8 units 6 units 3 units1 2 3 4 5 6 7 8 9
9 units
3 units
8 units
3 units
5 units
6 units
= 34 units

16. Get our your Geoboards! Make a length of 2 units. 1 unit 2 units

17. Use your Geoboard! 7 8 1 6 2 5 4 3 Make a 2 x 2 rectangle.
What is the perimeter of the rectangle? 6 1 5 2
The perimeter of the rectangle is 8 units. 4 3
It is NOT 8 SQUARE units because in perimeter we are NOT counting the SQUARES inside a shape. Instead, we are counting the unit LENGTHS of all the sides.

18. Use your Geoboard! 8 9 10 1 7 2 6 5 4 3 Make a 3 x 2 rectangle.
What is the perimeter of the rectangle? 1 7 2 6
The perimeter of the rectangle is 10 units. 5 4 3
It is NOT 10 SQUARE units because in perimeter we are NOT counting the SQUARES inside a shape. Instead, we are counting the unit LENGTHS of all the sides.

19. Use your Geoboard! 9 10 11 12
Make a polygon with a perimeter of 12 units. 1 8 2 7
Could your polygon look different? 6 5 4 3
YES!

20. Use your Geoboard! 10 9 11
Make a polygon with a perimeter of 14 units. 8 12 13 14 7 1
Could your polygon look different? 2 6 5 4 3
YES!

21. 12 units 3 x 3 12 units 4 x 2 8 units 1 x 3 10 units 4 x 1 4 units
Use your Geoboard to model the rectangle. Then write the perimeter on your dry-erase board.
RECTANGLE
PERIMETER
12 units
3 x 3
12 units
4 x 2
8 units
1 x 3
10 units
4 x 1
4 units
1 x 1

22. **BONUS** What is the AREA of each of the rectangles below?
PERIMETER
AREA
12 units
3 x 3
9 square units
16 units
4 x 2
8 square units
8 units
1 x 3
3 square units
10 units
4 x 1
4 square units
4 units
1 x 1
1 square unit

24. Complete problems 1-8 on pages 435 and 436.
Your Turn in your BOOK
Complete problems 1-8 on pages 435 and 436.

25. What is the perimeter of the shape below?
Exit Ticket (slide 1 of 2)
What is the perimeter of the shape below?

26. Exit Ticket (slide 2 of 2)
For which of the following situations would it be helpful to know the perimeter? (Choose more than one.)
If you want to put a wallpaper border around the top of your bedroom wall and you need to know how much wallpaper border to buy.
If you want to know how much tile you need for your kitchen floor.
If you are putting up a fence around a garden and want to know how much fencing to buy.
If you ran 3 laps around the outside of your house and you want to know how far you ran.