6th Class

Sorting Materials into Groups   Synopsis    

• The process of the classification of objects based on some known criteria is called grouping or sorting.

 

• We have a huge variety of objects present around us. Because of this, it is very important to classify objects into groups. If we know the properties of one member of the group, it would be very easy to predict the properties of the other members too.

Some of the properties of materials are:  

• Appearance

The various parameters governing the appearance of materials are colour/texture, roughness, shape, size, etc.  

• Lustre

Some materials shine when light falls on them. This property is generally observed in objects that more...

Separation of Substances   Synopsis      

• Matter can be broadly divided into two major groups "pure?? and "impure"

 

• Matter is made up of tiny particles called molecules. Molecules are further made of same or different kinds of atoms.

 

• Molecules of a substance have all the properties of that substance.

 

•  A pure substance is made up of only one type Of molecules and so it is called homogeneous substance, e.g., elements, compounds.

 

• An impure substance is made up of more than one type of molecules and it is called heterogeneous substance, e.g., mixtures.

 

•  A substance which is uniform in its composition and properties throughout is more...

Changes Around Us   Synopsis   Types of changes  

• Changes can also be classified based on the rate at which they take place.

 

• Fast change: The change that takes place within a very short time.

 

• Slow change: The change that occurs over a long period of time.

 

• Another factor for change is uniformity with respect to time.

 

• Periodic changes: Changes that repeatedly occur at fixed intervals of time e.g., change of seasons, formation of day and night.

 

•  Non-periodic changes: Changes that do not repeatedly occur at fixed intervals of time are non-periodic e.g., occurrence of storms and rain.

 

• Reversible change: A change more...

Water   Synopsis    

• Water is one of the vital components required for life and is called the compound of life.

 

•  Water has many properties that makes it unique and vital.

 

• The primary source of water on land is rain water.

 

• Water in its various forms is very abundant. About two-thirds of the earth is covered with water but most of it is not fit for drinking.

 

• Rain, hail and snow replenish water in rivers, lakes, ponds, wells and soil.

 

• Clouds are formed by floating droplets of water condensed in the higher layers of the air.

 

•  The exchange of water between land, more...

Air around us   Synopsis    

• Just like soil and water, air is also a part of the earth. Gases like hydrogen, oxygen, nitrogen, carbon dioxide and many other gases together form a mixture called air.

 

• Air and some other components form a very thin layer over the earth's surface. This layer is called the atmosphere.

 

• The different gases present in the air have unique properties and play a vital role in the creation and evolution of life.

 

• Air cannot be seen because it is transparent, colourless but it occupies space. When air moves, it is called wind which can be felt.

 

• The blanket of air surrounding the more...

Food and its Source   Synopsis    

• The substances which we eat every day, containing various edible components that provide us energy and materials which help our body to grow and remain healthy are called food.

 

• The materials that are needed to prepare a particular type of dish are called ingredients.

 

• The substances which one can eat are called edible.

 

• The germinating seeds, in the initial stage produce a white structure which grows out of the seed (radicle), are called sprouted seeds.

 

• The sweet juice produced by some flowers is called nectar.

 

• Honeybees collect nectar (sweet juices) from flowers and convert it into honey. Bees more...

Components of Food   Synopsis      

• The edible substances which we eat to obtain energy, materials required for growth, maintenance, development and to repair worn out tissue in our body is called food.

The sources of different components of food are listed below  

• Food on the basis of their role in the body, are classified into three major groups.

  more...

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