Fast and Slow Changes

Changes Around Us
Class 7

​In this Session Students will learn

1) To understand Natural and Man- Made Changes.
2) To understand Slow and Fast Changes.
3) To understand Periodic and Non- Periodic Changes.
4) To understand Desirable and Undesirable Changes.
5) Reversible and Irreversible Changes.

Changes that are brought about by human efforts are called Man-made changes.
Examples: Cooking Food, Turning gold into jewelry and making toys from plastics are examples of Man- Made changes.

Man- Made Changes

Changes that take place in nature by themselves are, called natural changes.
Example: Changes of Day and Night, Earthquakes and Growth of Living things are examples of Natural Changes

Natural Changes

​Slow and Fast Changes

Some changes take a long time to occur. Such changes are called slow changes. Examples: Changing of Season, Formation of Fossils.

The time taken by such changes can be hours, days, months or even years. On the other hand, changes that occur in a very short interval of time are called fast changes.
Examples: Fireworks, Burning of a piece of Paper.

Periodic and Non- Periodic Changes

Some changes repeat themselves at regular intervals of time. Such changes are called Periodic Changes.
Examples: Phases of the Moon, Occurrence of day and night.
Some changes do not repeat themselves at regular intervals of time. They occur randomly. Such changes are called Non- Periodic Changes.
Examples: The Occurrence of natural calamities like earthquakes and landslides, the spread of an epidemic, thunder, and lightning.

The changes that are harmful to us are called undesirable changes.
Example: Changes like flood,global & spoilage of food.

​Undesirable change

The changes that are useful to humankind are called desirable changes.
Example: Milk turning into curd, Fuel producing heat.

​Desirable Changes

Desirable & Undesirable changes

Thank You