Measurement of Length
Length means how long something is. We see many things
around us. Some are short in length such as paper clip, pencil, pen, notebook
etc., some are long in length such as tree, electric pole, cloth, room, train
track and some are very long such as distance between two places. We need to
select suitable unit to measure these lengths.
Standard Units of Measurement
In early days body parts were used to measure length.
But measurements taken by these means are not accurate and consistent. If we
use our hand span to measure length, the measurement taken by different person
will vary as our hand spans are not equal. Example: a child hand span is
smaller than the adult. So, hand span, hand, foot and cubit are not standard
units of measurement.
Units of Measurement
We observed that nonstandard unit of measurement does
not give same results. So, we need to use some standard units for measuring
lengths. Otherwise the measurements of an object will be different when
measured in different ways. We use different units of length to measure
Example: We measure length
of table edge, length of chalk, length of pencil etc. in centimeters (cm),
length of a room, height of tree, length of cloth, height of an electric pole
etc. in meters (m) and longer distance such distance between two places in
to be remembered
- The standard unit of length is meter.
- One meter is divided into 100 smaller units called
So, 1m = 100cm
- Short form of meter is “m”, centimeter is “cm” and
kilometer is “km”.
- 1000 m put together to make a bigger unit called a
of Measurement of Length
We use metric ruler, metric stick, tape, rod etc. to
Example 1: Length of blue rope is 7m and length of red
rope is 5m. Which rope is bigger and by how much?
Example2: Ria travelled 2km
by car and 5 km by bus. How much distance did she travel in all?