Chapter 6 — Measuring Length

Chapter 6 of the Class 4 Mathematics NCERT textbook (Maths Mela), "Measuring Length", introduces students to measuring length using metres and centimetres through hands-on activities like rope-making, long jumps, and treasure hunts, establishes the key relationship 1 m = 100 cm, and extends into finding the perimeter of shapes. Download the PDF and read the summary and Q&A below to prepare for class.

• Metres and Fractions of a Metre — Students recall from Grade 3 that length is measured in metres and revisit making ropes of 1 m, half metre (1/2 m), and quarter metre (1/4 m). The chapter highlights relationships such as 1 m = 1/2 m + 1/2 m and 1 m = 1/4 m + 1/4 m + 1/4 m + 1/4 m. These fractional lengths are then used practically to measure jumps, classroom dimensions, and distances.
• Centimetres and the Relationship 1 m = 100 cm — For small objects like an eraser or a rice grain, the chapter introduces the centimetre (cm) as the standard smaller unit. A metre scale is divided into 100 equal parts, each 1 cm long, giving the core fact: 1 metre = 100 centimetres. Students practise measuring objects such as fingernails, erasers, ants, and grains of wheat using a cm scale or measuring tape.
• Combining Metres and Centimetres — The chapter shows that a measurement can be expressed in two equivalent ways: Ramu reads his height as 120 cm while Shamu reads the same height as 1 m 20 cm — and both are correct. Students convert between the two forms (e.g., 2 m = 200 cm, 4 m 60 cm = 460 cm) through well exercises and a class height survey table.
• Perimeter — Length of a Boundary — The final section introduces perimeter as the length of the boundary of a closed shape, illustrated through Bhola's vegetable garden fencing activity. Students count boundary units, use 1 cm dot grids to find perimeters of different shapes, compare which boundary is longest or shortest, and draw their own shapes with a fixed perimeter of 20 cm.

1. 011 metre (m) = 100 centimetres (cm) is the key conversion fact in this chapter
2. 02Half metre = 50 cm and quarter metre = 25 cm, shown using ropes and a number line
3. 03Centimetres are used to measure small objects like erasers, fingernails, ants, and seeds
4. 04Students measure classroom objects using a cm scale and order them by length
5. 05Heights can be written two ways: 120 cm is the same as 1 m 20 cm
6. 06Perimeter is the length of the boundary of a shape or closed figure
7. 07Activities include a long jump competition, toy-car distance race, and a treasure hunt map measured in cm
8. 08A broken scale can still be used to measure length by noting the starting and ending numbers