Unit 7, Lesson 13
Perimeter and Area of Rectangles
Grade 5
Warm-up
What is the area of 1 window?
Record an estimate that is:
| too low | about right | too high |
|---|---|---|
Activity 1
| length (cm) | width (cm) |
|---|---|
- Jada draws a rectangle with a perimeter of 12 centimeters. What could be the length and width of the rectangle if all the side lengths are whole numbers? Use the table to record 5 possible answers.
-
Represent the length and width of each rectangle as a point on the coordinate grid.
- If Jada draws a square, how long and wide will it be?
- If Jada’s rectangle is 2.5 cm long, how wide is it? Represent this rectangle as a point on the coordinate grid.
- If Jada’s rectangle is 3.25 cm long, how wide is it? Represent this rectangle as a point on the coordinate grid.
Activity 2
| length (cm) | width (cm) |
|---|---|
- Jada draws a rectangle with an area of 16 square centimeters. What could be the length and width of the rectangle if all the side lengths are whole numbers? Use the table to record 5 possible answers.
-
Represent the length and width of each rectangle as a point on the coordinate grid.
- If Jada’s rectangle is 5 cm long, how wide is it? Represent this rectangle as a point on the coordinate grid.
- If Jada’s rectangle is 3 cm long, how wide is it? Represent this rectangle as a point on the coordinate grid.
- If Jada draws a square, how long and wide is it? Explain how you know.
Student Section Summary
We generated patterns and analyzed relationships between two different patterns.
Example: Both patterns start with 0.
| rule 1: Add 8. | 0 | 8 | 16 | 24 | 32 | 40 |
| rule 2: Add 2. | 0 | 2 | 4 | 6 | 8 | 10 |
Each number in Rule 1’s pattern is 4 times the value of the corresponding number in Rule 2’s pattern. Each number in Rule 2’s pattern is times the value of the corresponding number in Rule 1’s pattern. We represented 2 patterns together as points on a coordinate grid.
Coordinate plane. Horizontal axis, rule 1, 0 to 44, by 2's. Vertical axis, rule 2, 0 to 10, by 1's. A, 0 comma 0. B, 8 comma 2. C, 16 comma 4. D, 24 comma 6. E, 32 comma 8. F, 40 comma 10.
We also used points on a coordinate grid to represent other situations, such as the length and width of rectangles with a given area or perimeter.