Example 1
Find the perimeter and area of a rectangle with length 8 m and width 5 m.
- Perimeter = 2 × (length + width) = 2 × (8 + 5) = 2 × 13 = 26 m.
- Area = length × width = 8 × 5 = 40 m².
Answer: Perimeter is 26 m and Area is 40 m².
📗 Class 7 maths · session 9 of 12 · 60 minutes · 🎁 free with an account
Perimeter and area
Welcome aboard, superhero cadet! Captain Calc needs your help to measure shapes and secure HQ boundaries.
🤖 Written with Google's Gemini AI. A second AI solved all 55 questions without seeing the answers, and both agree. One of our teachers has not read it yet, so if something looks wrong, please tell us.
A complete lesson · 60 minutes
Teach it, see it, practise it, all on this page.
Open this page with your learner and work down it, or press Teach this lesson to go through it one step at a time on a big screen. Every section has something to do.
- Warm-up3 min
- Warm-up games5 min
- Perimeter and Area of Squares and Rectangles8 min
- Area of Parallelograms7 min
- Area of Triangles7 min
- Circles: Circumference and Area7 min
- Hero HQ Layout Mission6 min
- Triangle and Parallelogram Tower5 min
- Shield of Strength Circle Challenge6 min
- Quiz5 min
- Set the project1 min
By the end you can
- Calculate the perimeter and area of squares and rectangles
- Find the area of parallelograms using base and height
- Compute the area of triangles accurately
- Find the circumference and area of circles using pi
Before you start
- Basic multiplication and division of whole numbers
- Understanding basic 2D geometric shapes
Have ready
- Ruler and pencil
- Grid paper or notebook
Class 7 · CBSE, ICSE and state boards
Warm-up · think first
Captain Calc runs once around a square park of side 15 m. How total distance does he run in meters?
Show the answer
60 meters. A square has 4 equal sides, so 4 × 15 = 60 m.
Teacher tip: Ask students to trace the path around the boundary of a paper with their finger to feel what perimeter means.
🎮 Warm-up games · 5 quick games
Play with Captain Calc
Six minutes with Captain Calc. Vote, say why, then show the answer.
- Which measurement does not belong with the others: 24 cm, 36 cm², 18 cm, 40 m? (24 cm · 36 cm² · 18 cm · 40 m)
Answer: 36 cm² because it measures area, while the others measure linear length or perimeter. - Would you rather wrap a gift box of area 200 cm² or paint a floor of area 200 m²? (Wrap a gift box of 200 cm² · Paint a floor of 200 m²)
Answer: Wrap a gift box, because 200 cm² is much smaller than 200 m²! - If two rectangles have the same perimeter, they have the same area. (Always · Sometimes · Never)
Answer: Sometimes. A rectangle of 5 by 1 has perimeter 12 and area 5. A rectangle of 4 by 2 has perimeter 12 and area 8. - Captain Calc walks along a rectangular garden 10 m long and 6 m wide. He puts fence posts every 2 m along the border. How many posts does he need in total?
Answer: 16 posts. The total perimeter is 2 × (10 + 6) = 32 m. Spacing is 2 m, so 32 ÷ 2 = 16 posts. - Where do you see area and perimeter being used in real life around your town or school?
Answer: Fencing a field, putting tiles on a floor, framing a painting, painting a wall, or paving a playground.
Part 1 of 4 · learn, see, practise
Perimeter and Area of Squares and Rectangles
Perimeter is the total length around the boundary of a flat shape.
Area measures the surface space enclosed inside the boundary of a shape.
For a rectangle, Perimeter = 2 × (l + b) and Area = l × b. For a square of side s, Perimeter = 4 × s and Area = s².
Example 2
A square garden has a side of 12 m. Calculate its perimeter and area.
- Perimeter = 4 × side = 4 × 12 = 48 m.
- Area = side × side = 12 × 12 = 144 m².
Answer: Perimeter is 48 m and Area is 144 m².
Practise it
Start with the warm-up and go as far as you can. The stretch questions are meant to be hard.
Warm-up
Warm-up
Core
Core
Stretch 🔥
Stretch 🔥
Answers (for the teacher)
- 20
- 81
- 9
- 5
- 3200
- 100
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Unlocking the rest of this lesson gives you:
- Part 2: Area of Parallelograms, with practice at three levels
- Part 3: Area of Triangles, with practice at three levels
- Part 4: Circles: Circumference and Area, with practice at three levels
- Class activity 1: Hero HQ Layout Mission
- Class activity 2: Triangle and Parallelogram Tower
- Class activity 3: Shield of Strength Circle Challenge
- A 10-question quiz
- After-class project: Hero HQ Blueprint Designer
- Homework and a printable practice sheet with answers
- Teach mode and the minute-by-minute teacher's plan
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FAQ
Perimeter and area: questions
What is the main difference between perimeter and area?
Perimeter is the length of the outer boundary of a shape in units like cm or m. Area is the flat space inside the boundary measured in square units like cm² or m².
Why do we use 22/7 for pi (π)?
Pi (π) is the ratio of a circle's circumference to its diameter. The fraction 22/7 is a standard, simple approximation used in Class 7 maths.
How can I remember the area formula for triangles?
Think of a triangle as half of a parallelogram. Since a parallelogram area is base × height, a triangle area is half of that: (1/2) × base × height.
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