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:

We have learnt to compare weights of two different things by using a balance. We find that, comparing weight of a watermelon with bananas is not the same when it is compared with mangoes. We need to use standard measures to find the weight or mass of any object. We use Grams and Kilograms to find out how heavy things are.

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.

The standard unit of mass is the gram. The short form for gram is g. We use grams to weigh lighter things.

1000 grams makes one kilogram. We  write kilogram as kg. We use kilograms to weigh heavier things.

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

To measure the weight of a given object, we place the object on one pan of the balance and weights are placed on the other pan. 

Measuring Weight Balance

When two objects weigh the same, the two pans of the balance stay at the same level.

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


1. (i) kg

(ii) g

(iii) g

(iv) kg

2. Fill in the blanks:

Sugar Weighs
Watermelon Weighs


2. (i) 6 kg

(ii) 3 kg

3. Match the following:

Weights Matching


3. (i)  2

(ii)  3

(iii)  4

(iv)  1

4. Write T for true and F for false.

(i) The weight of lighter objects in measured in kg. _____

(ii) 1000 grams make 1 kg.

(iii) The pan with heavier objects moves upward. _____

(iv) 1 kg is heavier than 100 g.


4. (i) F

(ii) T

(iii) F

(iv) T

5. Fill in the blanks.

(i) 200g + 200g + 100g = _____g.

(ii) 500g + 500g = _____kg.

(iii) 500g + 200g + 200g + 100g = _____kg.

(iv) 2kg + 2kg + 10kg + 1kg = _____kg.


5. (i) 500g

(ii) 1kg

(iii) 1kg

(iv) 15kg

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

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