1. PowerPoint created by Parsheena Berch Resource: JBHM material Pictures: Google Images

2. Perimeter and Area

3. Cut-out shape of hand.
Stamp pad.
Stamp the entire cut-out hand with your thumbprints, making sure that all of the white space is covered.
Count the number of thumbprints it took to cover the teacher’s hand and record the results on the board.

4. What did you notice?
There is a difference among the number of thumbprints counted. Why do you think the number of thumbprints is so different?
Each person’s thumbprint is a different size resulting in a different number for many students.
You have just covered the area of my hand.
Do you think that using our thumbprints was a very accurate measure for finding the area? Why or why not?

5. If you wanted to wallpaper your room, would you want to count the number of thumbprints it took to cover the wall? Would that be an accurate measure?
Of course not, because your thumbprints would probably be a different size than your parents’.
How would you be able to make a good estimate of how much wallpaper you needed?
In order to do this, you would need a standard unit of measure.

6. Sheet of grid paper, glue, and scissors.
Glue one handprint from the previous activity onto the back of the grid paper and cut it out.
Turn the handprint over and count the number of squares covering the hand.
Each student should count to verify the area. Have students report their findings and post them on the board.
What do you notice about these numbers?
You should notice that these numbers are a lot closer to each other.
Why do you think most of us arrived at approximately the same number this time?
We each used the same unit of measure, square units. In order to find accurate measures, we need to use standard units of measure. Area is always expressed in square units. For example, if the grid paper you used was centimeter grid paper, then the area of my hand would be expressed in square centimeters.

7. You will be exploring the various formulas for finding the area of a shape.
Area is the amount of space inside a figure.
Area – the number of square units it takes to fill a space

8. Geoboards, grid paper, and Handout #1.
Form a 2 by 3 rectangle.
This is how to count the number of square units inside the rectangle to determine the area. You should count that the area is 6 square units.
Record the length, width, and area in the appropriate section on Handout #1.
Next, form a 3 by 3 square. This is how to count the number of square units inside the square to determine the area. You should find that the area is 9 square units and record the length, width, and area in the appropriate section on Handout #1.
You should form 4 additional rectangles on the geoboards, sketch them on the grid paper, and record the corresponding information.

9. You should discover that the length times the width of any rectangle equals its area.
Therefore the formula is, A = lw.

10. Find the area of the following rectangles without sketching them on grid paper.
Length = 5 cm, width = 3 cm
Length = 1.5 in, width = 2 in
Length = 3.25 mm, width = 2 mm
15 square centimeters
3 square inches
6.5 square mm

11. Share your results and explain your steps to the class.
What is the definition of a square?
It is a parallelogram with 4 equal sides and 4 equal angles.
That means it is also a type of rectangle.
Therefore, the length of the square times its width also equals its area. In this special case though, we know that the length and width of the side of the square are the same, which means, A = s • s or A = s2, where s represents the length of a side.

12. The exponent 2 or “squared”.
When you see a small 2 to the upper right of a number or variable, it means that the number is multiplied by itself. Teach them to read this as the number or symbol squared.
Also, teach them that area will be expressed in square measurements such as square feet, square inches, square centimeters, etc.

13. Find the area of the following squares without sketching them on grid paper.
Examples
Side = 4 cm
Side = 1.5 mm
Side = 0.05 in
16 square centimeters
2.25 square millimeters
square inches

14. Independent Practice: (DOK 2)
1) Side = 8 yards
2) Side = 2.3 feet
3) Side = 10 meters
64 square yards
5.29 square feet
100 square meters

15. Closure:
We have found perimeter of polygons by using formulas and/or just adding the lengths of the sides.
We have found the area of squares and rectangles. We have seen when it is important to be able to do this.
Do any of you have any questions about this topic?

16. Homework:
Handout #3 from JBHM binder