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Measurement of Length

Measurement of Length for Class 3 Math

Here the student will recall their previous learning from the measurement of length and learn more about height measurement. Also, the word problems on length for grade 3 will help the students relate the topic to real life.

The student will learn to

  • Identify the difference between length and height
  • Find the relation between cm and mm, the relation between m and mm, the relation between km and m
  • Convert km to m, convert m to cm, convert cm to mm
  • Apply height word problems in real-life situations

The learning concept is explained to class 3 students with examples, illustrations, and a concept map. At the end of the page, two printable measurements of length worksheets for class 3 with solutions are attached for the students.

Download the worksheets and solutions to assess our knowledge of the concept.

Length is a measure of how long something is. We use rulers or tape to measure lengths.

  • Most of the times, we measure the length in millimetres (mm), centimetres (cm), meters (m), and kilometres (km) as a unit of length. These are standard units of length.
  • In daily life, we use a centimetre scale to measure length.
  • The tailors in their shop use a metre scale to measure any cloth.

Uses of Ruler to Measure Length

  • The object to be measured should be kept properly on the scale such that one of its ends coincides with the zero (0) mark on the scale.
  • The object to be measured should be kept parallel to the scale and touching the scale.
  • While taking the reading of the other end of the object, the mark of the scale and your eyes should all be in a straight line on the scale.
  • Hence, the reading of the length from the ruler is 13 cm. The length of the pencil is 13 cm.

Also, height can be measured using scales or tapes. We use centimetres (cm) and metre (m) as units to measure height. Always start measuring from the 0 mark to get an accurate reading.

Relation Between cm-mm, m-cm and km-m

The standard unit of length is ‘Metre’. Conversion from one unit to another unit is easy if we know the relationship between the units.

  • Cm in MM: 1-centimetre length is equally divided into 10 small parts and each part is called a millimetre (mm).
cm Scale

So, 1 cm = 10 mm or 10 mm = 1 cm

  • M in Cm: 1-metre length is equally divided into 100 small parts and each part is called a centimetre (cm). So, So, 1 m = 100 cm or 100 cm = 1 m
  • Km-M: 1-kilometre length is equally divided into 1000 small parts and each part is called a metre (m). So, 1 km = 1000 m or 1000 m = 1 km

Conversion from cm to mm, m to cm, and km to m

How to Convert Cm to MM

  • To convert cm to mm, we multiply the length of the object by 10.

Example: Convert from 24 cm to mm.

Answer: 24 cm = 24 × 10 = 240 mm

Convert M to Cm

  • To convert m to cm, we multiply the length of the object by 100.

Example: Convert from 30 m to cm.

Answer: 30 m = 30 × 100 = 3000 cm

Convert Km to M

  • To convert km to m, we multiply the length of the object by 1000.

Example: Convert from 45 km to m.

Answer: 45 km = 45 × 1000 = 45000 m

relation between cm and mm

Word Problem on Length for Grade 3

  1. Sahil has to colour a 100 m bamboo. He is instructed to colour 20 m of the bamboo with red, 30 m with blue and 40m with orange. What length of the bamboo is left uncoloured?


Sahil coloured 20 m + 30 m + 40 m bamboo

20 m + 30 m + 40 m = 50 m + 40 m = 90 m

So, the uncoloured portion left is 100 m – 90 m = 10 m

Hence, 10m of the bamboo is left uncoloured.

2.Julie’s grandfather has a 3 m long ribbon. He decided to divide the length of the ribbon among his four grandsons and daughters. How much ribbon will each one get?


3 m = 3 × 100 cm = 300 cm

Grandfather has 4 grandsons and daughters.

So, each of them will get 300 cm ÷ 4 = 75 cm

Hence, each one will get 75 cm ribbon.



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