3. How much cardboard does it take to make a cereal box? Have you ever wondered?

4. Surface Area- the sum of the areas of all the faces

5. Do you see the RED face? What are the dimensions of this rectangle? 10 in. 4 in.

6. Do you see another face that is just like the RED face? Where is it located?

7. Yes, it’s on the back. 10 in. 4 in. 10 in. 4 in. The front is a face. It is identical to the back.

8. 40 in 2 The area of the front is 40 in ². That means the area of the back is also 40 in².

9. Do you see the BLUE face? What are the dimensions of this rectangle? 4 in. 7 in.

10. Do you see another face that is just like the BLUE face? Where is it located?

11. 4 in. 7 in. 4 in. The right side is a face. It is identical to the left side.

12. The area of the right side is 28 in ². That means the area of the left side is also 28 in². 28 in 2

13. Do you see the GREEN face? What are the dimensions of this rectangle? 10 in. 7 in.

14. Do you see another face that is just like the GREEN face? Where is it located?

15. The top is identical to the bottom. 10 in. 7 in. 10 in. 7 in.

16. The area of the top is 70 in ². That means the area of the bottom is also 70 in². 70 in 2

17. We just need to add all the areas of the sides together. + + + + 70 in 2 28 in 2 40 in 2 28 in 2 70 in 2 To find the total surface area, you add ALL the areas.

18. The total Surface Area for this rectangular prism is 40 + 40 + 28 + 28 + 70 + 70 = 276 in 2

19. It’s your turn to try one!

20. Find the surface area. 6 cm 3 cm 2 cm Area of top and bottom: 2 3 cm x 2 cm = 6 cm 2 Since there are two of these shapes, 12 cm 2 6 cm x 2 = 12 cm 2

21. Find the surface area. 6 cm 3 cm 2 cm Area of front and back: 2 3 cm x 6 cm = 18 cm 2 Since there are two of these shapes, 2 36 cm 2 18 cm 2 x 2 = 36 cm 2

22. Find the surface area. 6 cm 3 cm 2 cm Area of both sides: 2 6 cm x 2 cm = 12 cm 2 Since there are two of these shapes, 2 24 cm 2 12 cm 2 x 2 = 24 cm 2

23. Find the surface area. 6 cm 3 cm 2 cm Now add up the answers 12 cm 2 12 cm 2 36 cm 2 36 cm 2 +24 cm 2 +24 cm 2 72 cm 2

24. Formula for Surface Area of Rectangular Prisms SA = 2(lw) + 2(lh) + 2(wh) width height length

25. Formula for Surface Area of a Cube SA = 6(s 2 ) side Since all dimensions of a cube are the same, you only need to know the length of one side.

26. How about another method?

27. Notes for your binder: S. Area: OTHER METHODS 1) “Football” Method 2) “Butt” Method

28. “Butt” Method 5 in 2 in 9 in

29. “Butt” Method 3 in 5 in 10 in

30. “Football” Method 3 in 2 in 10 in

31. “Football” Method 5 in 4 in 8 in

32. You try this one! Use whichever method you prefer… 6 cm 2 cm 4 cm