This is one of the easiest methods of separating substances from each other. In this method, the impurities can be separated from the useful substance, simply by picking out by hand. This method can be specifically used for picking out substances which are slightly larger in size.
Example: Separating pebbles from fine sand.

This method is used widely on farmlands where large heaps of consumable crops are separated from the stalks. Crops are first sun dried and then separated from the grain. This process has been followed since ages wherein bullocks were being used to carry out the same. As time and technology  advanced, industrialisation gave rise to development of high performance machinery for carrying out processes like threshing.
Example: Separating the consumable grain from the crop.

In this method of separation, the substances are separated from each other by dropping them from a higher altitude and separating the lighter residue from the consumable crop. This method too, is very widely used on farmlands for separation of the heavier grain and the lighter stalk. As the mixture of the crop and the residual are dropped from a higher elevation, the air displaces the lighter material from the heavier one. 

Sometimes while preparing food, we come across instances where we have to separate substances which are extremely fine in nature and require a higher level of filtration. Sieving is a process where we use a sieve for separating the finer substances from the coarse impurities. Sometimes even after carrying out threshing and winnowing, we come across small stones and impurities in the raw food items, which need to be removed before the food can be cooked. Hence, sieving can help in this process.
Example: Separating sooji rava from fine stones.

There is a good possibility that there can still be impurities, despite carrying out the initial filtering. To overcome this, the mixture of substances can be immersed in water and the heavier substance settles in the bottom of the container. This process is called Sedimentation. After the material settles down, the useful substance remains there and the water is taken out. This is called Decantation. Despite doing decantation, there is a possibility that there is still some residue left in the container with the useful material. This can be separated out by a fine filter and the process is called Filtration.
Example: Separation of tea leaves from the tea solution.

Evaporation is a process where a substance in liquid state is converted to vapour state. It’s a very effective solution for separating out any kind of impurities from a liquid solution. The liquid solution is heated continuously, until all the liquid gets evaporated and what remains in the end, is the impurity in solid state.
Example: Separating salt from a saltwater solution using evaporation.

Understanding the concept of separation of substances is really important owing to the fact that it is something which is applicable in our day-to-day life and understanding it ensures that we are well acquainted with its applications. Studying these topics should be based on their application which facilitates a broader understanding of the topic.

1. What is the method of separation of substances?
   There are 6 commonly known methods of separation, which are as follows:
   A. Handpicking
   B. Threshing
   C. Winnowing
   D. Sieving
   E. Sedimentation, Decantation and filtration
   F. Evaporation
2. Why do we separate substances ?
   Substances need to be separated in order to either remove impurities or to use the separated substances individually.
3. Why are pebbles separated from sand?
   Pebbles act as an impurity in fine sand and in order to refine it, pebbles are removed.
4. What separation means?
   Separation means, separating the components of a substance, either to remove the impurities or to use them separately.