EVS / Science

Water Cycle

Class 4

🎯 Learning Objectives

📖 Let Us Begin!

Have you ever wondered where the rain comes from? Or where the water goes after it rains? Water keeps moving in a never-ending journey called the water cycle. The same water that dinosaurs drank millions of years ago is the water we use today!

In India, the monsoon season brings most of our rainfall. Farmers across the country wait eagerly for the rains. Let us explore how water travels, where it is found, and why we must protect it.

The Water Cycle -- Nature's Recycling

The water cycle is the continuous movement of water between the Earth and the sky. It has four main stages:

1. Evaporation: The sun heats the water in rivers, lakes, and oceans. The water turns into water vapour (a gas) and rises up into the air. You cannot see water vapour -- it is invisible. When wet clothes dry on a clothesline, the water evaporates into the air.

2. Condensation: As water vapour rises high into the sky, it cools down. The cool vapour turns back into tiny water droplets. Millions of these droplets come together to form clouds. The fog you see on cold winter mornings in Delhi or Lucknow is also condensation.

3. Precipitation: When clouds become heavy with water droplets, the water falls back to the Earth. This falling water is called precipitation. It can come as rain, hail, or even snow (like in Shimla and Kashmir in winter).

4. Collection: The water that falls collects in rivers, lakes, ponds, and oceans. Some water seeps into the ground and becomes groundwater. This groundwater fills our wells and borewells. Then the cycle starts all over again!

Think about it: When your mother boils water for tea and you see steam rising from the kettle, which stage of the water cycle is that?

Sources of Water

Water is found in many places on Earth. These are called sources of water.

SourceDescriptionIndian Example
RainWater falling from clouds; the main source of all fresh waterMonsoon rains from June to September
RiversLarge flowing bodies of water that carry water to the seaGanga, Yamuna, Brahmaputra, Godavari, Kaveri
LakesLarge bodies of still water surrounded by landDal Lake (Kashmir), Chilika Lake (Odisha)
Wells and BorewellsHoles dug deep into the ground to reach groundwaterCommon in villages across Rajasthan and Tamil Nadu
OceansHuge bodies of salt water covering most of the EarthArabian Sea, Bay of Bengal, Indian Ocean

Fresh Water vs Salt Water

Most of the water on Earth (about 97%) is salt water found in oceans and seas. We cannot drink salt water -- it is too salty and can make us sick.

Only about 3% of the Earth's water is fresh water. Fresh water is found in rivers, lakes, glaciers, and underground. This is the water we drink, cook with, and use for farming. Because fresh water is so little, we must use it carefully.

Think about it: If you filled 100 glasses with all the water on Earth, only 3 glasses would be fresh water. How important is it to save water?

Water Conservation -- Saving Every Drop

India faces water shortage in many areas, especially during summer. Here are ways we can conserve water:

Water Pollution -- Causes and Prevention

Causes of water pollution:

How to prevent water pollution:

Think about it: What would happen to the fish and other animals if we keep polluting our rivers?

📝 Key Words

WordMeaning
Water cycleThe continuous movement of water between the Earth and the atmosphere
EvaporationWater changing from liquid to water vapour (gas) due to heat
CondensationWater vapour cooling and turning back into tiny water droplets
PrecipitationWater falling from clouds as rain, hail, or snow
GroundwaterWater stored under the ground in soil and rocks
Fresh waterWater that is not salty; found in rivers, lakes, and underground
Water pollutionMaking water dirty and unsafe by adding harmful substances
⭐ Key Points to Remember

✏️ Practice Questions

A. Fill in the Blanks
1. When the sun heats water and it turns into vapour, it is called .
2. Water vapour cools and forms tiny droplets in a process called .
3. Water falling from clouds as rain or snow is called .
4. About % of Earth's water is salt water found in oceans.
5. Collecting rainwater from rooftops is called .
B. Multiple Choice Questions
1. Which is the correct order of the water cycle?
(a) Condensation, Evaporation, Collection, Precipitation
(b) Evaporation, Condensation, Precipitation, Collection
(c) Precipitation, Collection, Condensation, Evaporation
2. Which of these is a source of fresh water?
(a) Arabian Sea(b) Indian Ocean(c) River Ganga(d) Bay of Bengal
3. Which of these causes water pollution?
(a) Planting trees(b) Rainwater harvesting(c) Dumping factory waste in rivers
C. Short Answer Questions
1. Name the four stages of the water cycle.
2. Write two differences between fresh water and salt water.
3. List three ways to save water at home.
🎨 Think and Do -- Fun Activity

Make a Water Cycle in a Bag: Take a clear plastic zip-lock bag. Pour a small amount of water into it and add a drop of blue ink. Seal the bag tightly and tape it to a sunny window. Over a few hours, watch what happens!

Draw what you observe in the boxes below and label each stage of the water cycle:

After 1 HourAfter 3 HoursAfter 5 HoursStage Name

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Learning Objectives
Let Us Begin!

Have you ever wondered where the rain comes from? Or where the water goes after it rains? Water keeps moving in a never-ending journey called the water cycle. The same water that dinosaurs drank millions of years ago is the water we use today!

In India, the monsoon season brings most of our rainfall. Farmers across the country wait eagerly for the rains. Let us explore how water travels, where it is found, and why we must protect it.

The Water Cycle -- Nature's Recycling

The water cycle is the continuous movement of water between the Earth and the sky. It has four main stages:

1. Evaporation: The sun heats the water in rivers, lakes, and oceans. The water turns into water vapour (a gas) and rises up into the air. You cannot see water vapour -- it is invisible. When wet clothes dry on a clothesline, the water evaporates into the air.

2. Condensation: As water vapour rises high into the sky, it cools down. The cool vapour turns back into tiny water droplets. Millions of these droplets come together to form clouds. The fog you see on cold winter mornings in Delhi or Lucknow is also condensation.

3. Precipitation: When clouds become heavy with water droplets, the water falls back to the Earth. This falling water is called precipitation. It can come as rain, hail, or even snow (like in Shimla and Kashmir in winter).

4. Collection: The water that falls collects in rivers, lakes, ponds, and oceans. Some water seeps into the ground and becomes groundwater. This groundwater fills our wells and borewells. Then the cycle starts all over again!

Think about it: When your mother boils water for tea and you see steam rising from the kettle, which stage of the water cycle is that?

Sources of Water

Water is found in many places on Earth. These are called sources of water.

SourceDescriptionIndian Example
RainWater falling from clouds; the main source of all fresh waterMonsoon rains from June to September
RiversLarge flowing bodies of water that carry water to the seaGanga, Yamuna, Brahmaputra, Godavari, Kaveri
LakesLarge bodies of still water surrounded by landDal Lake (Kashmir), Chilika Lake (Odisha)
Wells and BorewellsHoles dug deep into the ground to reach groundwaterCommon in villages across Rajasthan and Tamil Nadu
OceansHuge bodies of salt water covering most of the EarthArabian Sea, Bay of Bengal, Indian Ocean
Fresh Water vs Salt Water

Most of the water on Earth (about 97%) is salt water found in oceans and seas. We cannot drink salt water -- it is too salty and can make us sick.

Only about 3% of the Earth's water is fresh water. Fresh water is found in rivers, lakes, glaciers, and underground. This is the water we drink, cook with, and use for farming. Because fresh water is so little, we must use it carefully.

Think about it: If you filled 100 glasses with all the water on Earth, only 3 glasses would be fresh water. How important is it to save water?

Key Words and Meanings
WordMeaning
Water cycleThe continuous movement of water between the Earth and the atmosphere
EvaporationWater changing from liquid to water vapour (gas) due to heat
CondensationWater vapour cooling and turning back into tiny water droplets
PrecipitationWater falling from clouds as rain, hail, or snow
GroundwaterWater stored under the ground in soil and rocks
Fresh waterWater that is not salty; found in rivers, lakes, and underground
Water pollutionMaking water dirty and unsafe by adding harmful substances
Water Conservation -- Saving Every Drop

India faces water shortage in many areas, especially during summer. Here are ways we can conserve water:

Water Pollution -- Causes and Prevention

Causes of water pollution:

How to prevent water pollution:

Think about it: What would happen to the fish and other animals if we keep polluting our rivers?

Examples from Daily Life
Example 1: The Water Cycle at Home

When Priya's mother boils water, steam rises from the pot. This is evaporation. The steam hits the cool lid and tiny water drops form on it. This is condensation. When the drops become heavy, they fall back into the pot. This is like precipitation. Priya can see the water cycle happening right in her kitchen!

Example 2: Rainwater Harvesting in Chennai

Arjun's school in Chennai has a rainwater harvesting system. During the monsoon, rainwater from the school roof flows through pipes into a large underground tank. The school uses this stored water for the garden and for cleaning during the dry months.

Example 3: The Polluted Yamuna

The Yamuna river passes through Delhi. Factories and drains release dirty water into it. The river looks dark and smells bad in many places. The government is working to clean it, but everyone must help by not throwing waste into the river.

Key Points to Remember
Practice Questions

A. Fill in the Blanks

  1. When the sun heats water and it turns into vapour, it is called .
  2. Water vapour cools and forms tiny droplets in a process called .
  3. Water falling from clouds as rain or snow is called .
  4. About % of Earth's water is salt water found in oceans.
  5. Collecting rainwater from rooftops is called .

B. Multiple Choice Questions

  1. Which is the correct order of the water cycle?
    (a) Condensation, Evaporation, Collection, Precipitation
    (b) Evaporation, Condensation, Precipitation, Collection
    (c) Precipitation, Collection, Condensation, Evaporation
  2. Which of these is a source of fresh water?
    (a) Arabian Sea(b) Indian Ocean(c) River Ganga(d) Bay of Bengal
  3. Which of these causes water pollution?
    (a) Planting trees(b) Rainwater harvesting(c) Dumping factory waste in rivers

C. Short Answer Questions

  1. Name the four stages of the water cycle.
  2. Write two differences between fresh water and salt water.
  3. List three ways to save water at home.
Think and Do -- Fun Activity

Make a Water Cycle in a Bag: Take a clear plastic zip-lock bag. Pour a small amount of water into it and add a drop of blue ink. Seal the bag tightly and tape it to a sunny window. Over a few hours, watch what happens!

Draw what you observe in the boxes below and label each stage of the water cycle:

After 1 HourAfter 3 HoursAfter 5 HoursStage Name