What is Mass?

In third grade measurement of mass we will discuss about what is mass, standard unit of mass or weight etc,. The standard unit of weight or mass is gram and kilogram is the bigger unit of weight. We write as 'g' and kilogram as 'kg'. Kilogram is used to measure the heavier objects like a watermelon, school bag whereas gram is used to measure lighter objects like a chocolate, a tennis ball etc. 

What is mass?

The quantity of matter in an object is called its mass. We must know that the meaning of mass of a body is different from that of the weight of that body. The two terms, mass and weight, are different in the real sense. But in the initial stages for children, the difference is ignored and we use the terms weight and mass in the same sense. Weight of an object changes from place to place, above and below the surface of the earth, but mass of a body never changes. We know, in the surface of the earth we take the units of mass similar to the units of weight.

Standard unit of Mass or Weight:

The standard unit of mass is kilogram and in short it is written as kg. It is used to measure the mass of heavy objects such as bags of grain, stones, etc. The smaller unit of mass is gram and in short it is written as g. It is used to measure the mass of lighter objects.

We know, 1000 g = 1 kg or 1 kg = 1000 g

In a grocery shop we can see different weights to weigh different things.

Now, observe the following pictures. The shopkeeper is weighing vegetables in kilograms and grams and the girl is measuring her weight in kilograms. 

Measuring Vegetables
Measurement of Weight

The standard weights or blocks are used by a shopkeeper to weight different objects with the help of a common balance.

Standard Weights

There are various types of balance scale available now a days to measure weights of different objects. Some of these scales have digital display to show the weight of an object.

Balance Scales

Questions and Answers on Measurement of Mass:

1. Circle the best unit that you would use to measure the weights of the following objects.

Rice Weight
Soap Weight
Cookies Weight
Cycle Weight


(i) kg

(ii) g

(iii) g

(iv) kg

2. Fill in the blanks:

Sugar Weighs
Watermelon Weighs


(i) 6 kg

(ii) 3 kg

3. Match the following:

Weights Matching


(i)  2

(ii)  3

(iii)  4

(iv)  1

From the above definition we know what is mass and Click Here to know more about the unit of mass.

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Conversion of Standard Unit of Mass

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