Question

what are the advantages of sorting things into groups.

Answer 1

Objects around us have different shapes, colours and uses. Some of the objects are found in nature while others are man-made.

Objects are made of materials. Materials are the substances used to make things. For example, wood pulp is the material from which paper is made.

Same material can be used to make different types of objects. For example, glass can be used to make bowls, bulbs, window panes etc. The same object can be made of different kinds of materials. For example, a chair is made of wood, plastic or iron.

Some objects are made up of a combination of several materials. For example, a wooden knife and a plas stic knife Material can be classified as naturally occurring materials and man–made materials. 

Naturally occurring materials are found in nature. E.g., cotton, marble etc. 

Man-made materials are prepared by human beings. For example, plastic, steel, polyester etc.

Different materials have different characteristic properties. These properties include appearance, hardness, transparency and solubility. Appearance includes colour, lustre, texture and physical state. Materials can exist in solid, liquid or gaseous state.

The materials that can be compressed easily are known as soft materials. Some materials are hard materials as they cannot be compressed. Based on transparency, materials can be classified as transparent, translucent and opaque materials.

Transparent materials allow light to pass through them. For example, water, glass etc.

Translucent materials allow only a part of light to pass through them. For example, oily paper, ground glass etc.

Opaque materials do not allow light to pass through them. For example, wood, metals, cardboard etc.

The materials which dissolve in water are called soluble materials. For example, sugar, salt etc. Insoluble materials do not dissolve in water. For example, sand, kerosene etc.

Material that is lighter than water floats in water. E.g., plastic Material that is heavier than water sinks in water. e.g., iron nail etc. Grouping of objects together with similar properties is called sorting. The materials can be grouped on the basis of similarities or differences in their properties. 

Grouping helps in gaining systematic knowledge of things. It also gives a general idea about all members of a group and the differences between members of different groups. It is convenient to work with all members of a group knowing their properties.

hope it helps 
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keep asking but not in exams

Answer 2

Sorting material into groups is in order to classify the material as per its usage. Sorting material into groups is necessary.
Like for disposal : For proper disposal of objects, it is important to sort them into groups of degradable and biodegradable substances