Schooling · Class 6 · Mathematics · Perimeter and Area · Chapter on a page
CBSE Class 6 · Mathematics · NCERT Ganita Prakash
Perimeter and Area: chapter on a page
A cut of Shishya's notes for this chapter: the first paragraph of the introduction and the key ideas, formulas and facts, common mistakes and quick revision lists, word for word. Nothing is added or reworded; the worked examples are left out (they are on the chapter page).
About the notes: Written by Shishya's AI on 26 Sept 2026 from the chapter's title and class level, in Shishya's own words — not a copy or summary of the textbook. Read the official chapter for the book's own text, activities and exercises.
This note's current text has no applied fact-check on record.
Mind map
Drawn from the same notes by a fixed rule (no AI): each label is the item's own words — its bold term, its label before a colon, a short formula as written, or its first words.
The mind map as a list
- Key ideas
- Perimeter
- Area
- rectangle
- square
- Two shapes can have the same…
- To find the area of an irregular…
- Perimeter is measured in simple…
- Formulas and facts
- Rectangle
- Square
- 1 metre = 100 centimetres, so 1 m² =…
- Perimeter tells you "how long is the…
- Area tells you "how much space is…
- Worked examples
- Finding perimeter and area of a…
- Finding the side of a square from…
- Comparing two rectangles
- Watch out for
- Confusing perimeter and area
- Writing the unit for area as "cm"…
- Forgetting to multiply by 2 in the…
- Thinking same perimeter means same…
- Using different units for length and…
What this chapter is about
This chapter teaches you two ways to measure flat shapes. The first is perimeter, which means the total length of the boundary around a shape. The second is area, which means how much surface a shape covers.
Key ideas
- Perimeter is the total distance around a closed shape. You add up all the side lengths.
- Area is the amount of flat surface inside a shape. We measure it in square units like square centimetres (cm²) or square metres (m²).
- For a rectangle, perimeter = 2 × (length + breadth). Area = length × breadth.
- For a square, perimeter = 4 × side. Area = side × side.
- Two shapes can have the same perimeter but different areas, or the same area but different perimeters.
- To find the area of an irregular shape drawn on a square grid, count the full squares and estimate the part squares.
- Perimeter is measured in simple length units (cm, m). Area is measured in square units (cm², m²).
Formulas and facts to remember
- Shape: Rectangle · Perimeter: 2 × (length + breadth) · Area: length × breadth
- Shape: Square · Perimeter: 4 × side · Area: side × side
- 1 metre = 100 centimetres, so 1 m² = 10 000 cm².
- Perimeter tells you "how long is the boundary."
- Area tells you "how much space is covered."
Common mistakes
- Confusing perimeter and area → Remember: perimeter is the boundary (add sides), area is the inside (multiply length and breadth).
- Writing the unit for area as "cm" instead of "cm²" → Area is always in square units because you multiply two lengths.
- Forgetting to multiply by 2 in the rectangle perimeter formula → A rectangle has two lengths and two breadths, so you must double the sum.
- Thinking same perimeter means same area → Two shapes with equal perimeter can cover different amounts of space.
- Using different units for length and breadth without converting → Always convert to the same unit (both in cm or both in m) before calculating.
Quick revision
- Perimeter = total length of all sides around a shape.
- Area = space covered inside a shape, measured in square units.
- Rectangle: Perimeter = 2 × (l + b), Area = l × b.
- Square: Perimeter = 4 × side, Area = side × side.
- Same perimeter does not mean same area.
- Always write area with a "²" in the unit.