Perimeter
Find the perimeter of a rectangle that has the side measurements of 4cm and 3cm
Find the area of a rectangle that is 3cm wide and 6cm long.
The area of the rectangle is 18cm.
6 x 3 = 18cm
Which rectangle has a greater area? 3cm x 4cm or 2cm x 6cm
They both have the same area!
3x4 = 12
2x6 = 12
You’re designing a picture frame. What units would you use to measure its perimeter?
You should use centimeters because meters would be too large, and millimeters would be too small.
A rectangle has a length of 8 cm and a perimeter of 24 cm. What is its width?
The width is 4cm
A rectangle has an area of 24cm2 and has a side length of 4cm long. What is the width of the rectangle?
The width of the triangle is 6cm.
6 x 4 = 24.
Two rectangles both have a perimeter of 20cm. Which one could have a larger area? Why?
the rectangle that’s closest to a square, because a shape with sides more equal has the largest area for the same perimeter.
What is the 5 cm × 5 cm square — because equal sides enclose the most space
You have 12 m of fencing. Draw one possible rectangular garden and label its sides.
One possibility is:
a rectangle with a perimeter of 8 + 8 + 2 + 2
True or False: Two rectangles can have the same perimeter but different areas
True
If the length increases but the width stays the same, what happens to the area?
area increases, because a longer rectangle covers more space?
A playground is 8 m by 5 m. How many 1 m² tiles would cover the space?
The sides of a rectangle are 5 m and 2 m. If each side doubles, what happens to the perimeter?
The perimeter also doubles
Explain how doubling one side of a rectangle doubles the area?
Because when you make one side twice as long, you have twice as many squares covering the same width. So, the total area doubles.
Compare a 4 × 5 rectangle and a 2 × 9 rectangle. Which has the larger perimeter?
The 2 × 9 rectangle has the larger perimeter (22 cm)
A rectangular rug has an area of 30m². If it’s 5m long, what’s its width?
The width would be 6m because 5x6 = 30.
Create your own rectangle with a perimeter of 30 cm. What could its side lengths be?
Possible answers:
- 9 cm × 6 cm
- 11 cm × 4 cm
- 13 cm × 2 cm
- 10 cm x 5 cm
Design a rectangle with an area of 36cm2. How many different sets of side lengths can you find?
- 1cm x 36cm
- 2 cm x 18cm
- 3cm x 12cm
- 4cm x 9cm
- 6cm x 6cm
Design two rectangles that have the same area but different perimeters
Example:
Rectangle 1: 6 × 4
- Area: 6 × 4 = 24
- Perimeter: 6 + 6 + 4 + 4= 20
Rectangle 2: 8 × 3
- Area: 8 × 3 = 24
- Perimeter: 8 + 8 + 3 + 3 = 22
Create your own real-world rectangle (e.g., a sports field, poster, garden) and explain how you’d measure both its perimeter and area.
Example answer: I would make a small garden that is 6 meters long and 3 meters wide. To find the perimeter I would add up all the sides. To find the area, I would multiply the length by the width.