Page 104 - Viva ICSE Science 4 : E-book

Cubit Handspan Foot span Arm length Arm span

All the above mentioned units of measurement are ancient. Since the size of body parts
diff er from person to person, these measures do not give accurate measurement results.

These are non-standard ways of measurement. Therefore, we need to have a standard
unit for measuring things. Standard units are the fi xed units of measurement that we

use to measure the accurate size or quantity of objects. Let’s learn about the standard
units that are used in everyday life.

Measurement of Length

The length is the distance between the two ends of an object. Metre (m) is the standard

unit of length. Centimetre (cm), millimetre (mm) and kilometre (km) are the other units of
length. Objects with long lengths are measured in metres, and even more long lengths
are measured in kilometres. The objects having short lengths are

measured in centimetres, while the shorter lengths are measured Did You Know!
in millimetres. We usually use a metre ruler, metre rod or measuring 2.5 centimetres
make an inch.
tape to measure the length of an object. All these measuring tools
have centimetres or inches marked on them.

Ruler Measuring tape

Metre rod

• A metre rod is used by a cloth dealer to measure the length of cloth materials.

• A measuring tape is commonly used by a tailor.

• A ruler is used to measure small lengths.

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