Measuring Length – Class 4 Maths Chapter 6 Notes & NCERT PDF

Class 4MathematicsChapter 6NCERT book: Maths Mela - Class 4

Notes and a simple summary of Chapter 6 of the NCERT Class 4 Mathematics book, with the official chapter PDF, flashcards, an MCQ quiz and an AI tutor for your doubts.

🎧 Listen to the content

Chapter 6: Measuring Length

Introduction

Children see students measuring things around them and learn that height, width, depth and breadth are all kinds of length. Building on Grade 3, where lengths were measured in metres with ropes, this chapter adds a smaller unit, the centimetre, and introduces the perimeter, the length of the boundary of a shape.

What's in this Chapter

Let Us Observe: Children decide whether statements about their classroom are correct, for example "The height of most students in my grade is more than a metre" or "The length of my arm is less than a metre".

Measuring is fun: Using 1 m, half metre and quarter metre ropes, children notice 1 m = 1/2 m + 1/2 m and 1 m = 1/4 m + 1/4 m + 1/4 m + 1/4 m. They draw 1 m, 5 m and 10 m lines and walk, jump and crawl on them, hold a long jump competition, and estimate the length and breadth of the classroom.

Guess the length: Pictures of a blue whale (about 30 metres), buses, cricket bats, ostriches and crocodiles help children compare big lengths.

Measuring small things: An eraser or a rice grain needs a smaller unit. A metre scale is divided into 100 equal parts; each part is a centimetre (cm). So 1 m = 100 cm, 1/2 m = 50 cm and 1/4 m = 25 cm. Chutki uses a tailor's measuring tape to track how tall her plant grows.

Let Us Do: measure objects with a scale and order them; estimate things less than, equal to or more than 1 cm (fingernail, ant, grain of wheat, rajma seed); measure how far toy cars roll from a ramp; find the shortest route in a treasure hunt map; trace and measure your hand and use it to estimate lengths; measure with a broken scale; fill a number line in cm and m.

Word problem: A board is 2 metres long and a border sticker is 20 cm long, so 10 stickers are needed.

Metres and centimetres: Ramu reads his height as 120 cm and Shamu as 1 m 20 cm. Pinki shows both are correct because 1 m 20 cm = 100 cm + 20 cm = 120 cm. Well depths are matched: 1 m 40 cm = 140 cm, 2 m 30 cm = 230 cm, 4 m 60 cm = 460 cm, 5 m 50 cm = 550 cm.

Fencing and lacing: Bhola puts bricks around his vegetable garden. The length of the boundary of a shape is its perimeter. On 1 cm dot grids children find and compare perimeters, look for shapes with the same perimeter, estimate perimeters of a desk and blackboard, and draw three shapes with a perimeter of 20 cm.

Key Ideas

Height, breadth, width and depth are all lengths.

1 metre = 100 centimetres.

Small lengths are measured in cm; big lengths in m.

Perimeter is the length all the way around a closed shape.

Different shapes can have the same perimeter.

Words to Learn

Length (लंबाई), Height (ऊँचाई), Breadth (चौड़ाई), Depth (गहराई)

Metre (मीटर), Centimetre (सेंटीमीटर)

Scale (पैमाना), Measuring tape (मापने का फीता)

Estimate (अनुमान)

Boundary (सीमा), Perimeter (परिमाप)

Tips for Parents & Teachers

Measure family members' heights on a wall and write them in cm and in m and cm.

Measure the child's hand span and use it to estimate the length of a table.

Walk around a small park or room and count steps to feel its perimeter.

Let children measure how far toy cars roll down a book ramp.

Common Mistakes

Starting to measure from 1 instead of 0 on the scale.

Thinking 1 m 20 cm and 120 cm are different lengths.

Mixing metres and centimetres when comparing (for example comparing 2 m with 150 cm without converting).

Counting dots instead of the gaps between dots when finding perimeter on a dot grid.

The book's exercise line "__ m = 800m" should read "__ m = 800 cm"; the answer is 8 m.

💡 Key Learning Points

✓Height, breadth, width and depth are all measurements of length.
✓The centimetre is a smaller unit than the metre, and 1 m = 100 cm.
✓Lengths can be written in cm or in m and cm, for example 120 cm = 1 m 20 cm.
✓Estimating first and then measuring builds a sense of size.
✓Perimeter is the length of the boundary of a closed shape.

👨‍🏫 Teaching Tips

→Revise metre ropes from Grade 3, then let children make half and quarter metre ropes.
→Mark 1 m, 5 m and 10 m lines in the playground for walking, jumping and crawling.
→Show a metre scale and point out the 100 equal parts; clarify that 100 is not the number of marks but the number of centimetre gaps.
→Run the long jump and toy car ramp activities, recording estimates and actual measurements.
→Let children measure each other's heights and record in both cm and m-cm.
→Use 1 cm dot grids to find perimeters by counting sides, and ask children to draw shapes with a 20 cm perimeter.

📋 Assessment Questions

Can the child measure an object with a scale starting from 0?
Can the child convert between m and cm, for example 4 m 60 cm = 460 cm?
Can the child estimate whether an object is less than, equal to or more than 1 cm or 1 m?
Can the child find the perimeter of a shape on a dot grid?
Can the child solve the sticker problem: 2 m board, 20 cm stickers?

Ask the AI tutor about Class 4 Mathematics Chapter 6

Get question answers, important questions, a quick MCQ quiz or a simple explanation of “Measuring Length”. Free — sign in with Google.

How the AI tutor works →