Science Unit 2 of Term 2 (Water)

Science Unit 2 of Term 2 (Water)

by S. Abdur Rahman, Your Science Teacher, And Sarah Ma'am, Assistant Co-Ordinating Teacher

​Learning Objectives:-

• After learning this lesson, students will be able to:-

• 1.understand the change of states in water.

• 2. describe the water cycle.

• 3. explain the importance of water cycle.

• 4. summarise rainwater harvesting and its uses.

​Introduction:-

• ​Water is the most abundant and precious resource on the Earth.

• It is found in oceans, seas, rivers, streams, lakes, ponds and even under the ground.

• All living things need water to live and to do many other activities.

• ​​To Explain it to You more Clearly:-

• ​Water (chemical formula H₂O) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, even though it provides no calories or organic nutrients. Its chemical formula, H₂O, indicates that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. The hydrogen atoms are attached to the oxygen atom at an angle of 104.45°. "Water" is the name of the liquid state of H₂O at standard conditions for temperature and pressure.

• ​A number of natural states of water exist. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice may precipitate in the form of snow. The gaseous state of water is steam or water vapor.

• ​Water plays an important role in the World Economy. Approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a major source of food for many parts of the world. Much of the long-distance trade of commodities (such as oil, natural gas, and manufactured products) is transported by boats through seas, rivers, lakes, and canals. Large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a wide variety of substances both mineral and organic; as such it is widely used in industrial processes, and in cooking and washing. Water, ice and snow are also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, diving, ice skating and skiing.

• ​Water covers approximately 70.9% of the Earth's surface, mostly in seas and oceans. Small portions of water occur as Ground Water (1.7%), in the glaciers and the ice caps of Antarctica and Greenland (1.7%), and in the air as vapor, clouds (consisting of ice and liquid water suspended in air), and precipitation (0.001%).Water moves continually through the water cycle of evaporation, transpiration (evapotranspiration), condensation, precipitation, and runoff, usually reaching the sea.

​I. Change of States in Water:-

We have already learnt about this in the previous classes.​

​Let us learn more about water in this lesson.

Multiple Choice

Question 1:-

More to Know:-

Our Human Body Consists of ______ Percent of Water.

• 75%

• 80%

• 50%

• 100%

​1. Water occurs naturally in three forms: ice, water and water vapour.

​2. These forms are also called states of water. Ice is in solid form, water is in liquid form and water vapour is in gaseous form.

​3. These states occur naturally because of temperature changes. Water becomes ice in cold regions, remains as water in oceans/rivers and becomes water vapour due to the heat of the Sun.

Open Ended

Question 2:-

Fill in the boxes given below with correct answers:-

(Liquid, Solid, Melting, Freezing, Cooling, Heating, Gas)

​SOILD STATE OF WATER:- ICE

​Ice is a solid form of water.

At temperature below 0 Degree Celsius, water becomes ice.

This process is called freezing.

​LIQUID FORM OF WATER:- WATER

​Water in liquid state is available in water bodies such as oceans, river, waterfalls etc.

​GASEOUS STATE OF WATER:- VAPOUR

​Water becomes water vapour as the temperature increases due to heat.

Heating forms a white mist of extremely small water droplets in the air known as water vapour.

Open Ended

Question 3:-

Higher Order Thinking Skills:-

Write any two water bodies in your area.

Open Ended

Question 4:-

Try to Answer:-

Why water is a good example for all states of matter?

Multiple Select

Question 6:-

Fill water in an ice tray and keep it in the freezer. After few hours, take it out. What happened to the water?

• The Water is Solidified.

• The Water turns to Ice.

• Liquid Water turns to Solid because of Freezing.

• None of these

Multiple Choice

Question 7:-

Now keep this ice tray on a table for some time. What happens to the ice?

• Nothing Happens.

• The Ice starts to Melt.

• None of these

• The Ice turns to Gaseous Vapour.

Multiple Choice

Question 8:-

Pour water from the ice tray into a kettle. Ask an elder at your home to heat the kettle and observe the mouth of the kettle when the water starts boiling. What do you see?

• Gas

• Water

• Boiling

• Vapour

• All of these

2.​ Water Cycle:-

​In nature, water keeps changing its state. Let us see how this happens. Due to the Sun‛s heat, water in oceans and rivers changes into water vapour and rises up

Water becoming water vapour on heating is called evaporation.

• The water vapour, when comes into contact with cool air, becomes water droplets. This is called condensation.

• The water droplets combine to form clouds. The water droplets continue to combine, and they become big and heavy. These water droplets then fall down as rain. This is called precipitation.

• In colder places, combined water droplets come down as snow, sleet or hail. This continuous change of water from one state to another in nature is called Water cycle.

• Water Storage (Lake, Ocean) Water Cycle.

• Water Cycle The continuous cycle through which water is circulated by different processes like evaporation, condensation and precipitation is called water cycle.

Open Ended

Question 9:-

What happens to the water in a wet cloth?

Multiple Choice

Question 10:-

In the water cycle, _______ is Involved.

• Only Condensation

• Only Evaporation

• Only Precipitation

• All of them are Involved

• Only Condensation and Evaporation

​Importance of Water Cycle:-

• ​To improve the availability of ground water.

• To control the Earth‛s temperature.

• To provide water to plants and animals especially humans

• To recycle the Earth‛s supply of water constantly.

Open Ended

Question 14:-

Is water cycle important for farming? Why?

Open Ended

Question 15:-

Why is water cycle important to human?

Open Ended

Question 16:-

Name the process which is responsible for the formation of droplets on the surface of a glass of cold drink.

Multiple Choice

Question 17:-

_______ of our brain‛s mass consists of ______.

• 100% , Water

• 75% , Fat

• 73% , Fat

• 73% , Water

Multiple Choice

Question 18:-

The_______ region has about 70% of the worlds fresh water.

• Pacific

• Atlantic

• Antartic

• Indian

3.Rain Water Harvesting:-​

​‘Rainwater harvesting‛ is the process of collecting and storing rainwater for future use. Rainwater can be collected in natural reservoirs or artifi cial tanks. Roof top harvesting is also a type of rainwater harvesting. The rainwater on the top of the building is collected and passed into the ground through pipes. Water passing through the pipes enters the pit which consist of gravels and Coarse sand. As it passes impurities are fi ltered and stored as ground water.

​Do you Know?

​1 inch of rainfall on a 2,000 sq.ft. roof is equal to 4,800 litres of water.

​Benefits of Rain Water Harvesting:-

• ​Rain water harvesting is the only way to conserve rain water because:-

• ​It increases the ground water level

• It can be used for agriculture

• It increases the availability of water for living things.

Open Ended

Question 20:-

List out some other benefits of rain water harvesting.

Open Ended

Question 21:-

Suggest some ideas to save rainwater in your school.

​More to Know:-

• The rain water harvesting was launched in the year 2001 by the Tamil Nadu government.

• Tamil Nadu is the first Indian state which made rainwater harvesting as mandatory.

Open Ended

Question 22:-

Rain water harvesting has an important role to protect our environment. Give Reason.

Book Back Exercises:-​

​Exercise 1:-

​Choose the Correct Answers:-

Multiple Select

Question 23:-

Water is the most __________ resource on the Earth.

• Precious

• Common

• Rare

• Solid

Multiple Choice

Question 24:-

Water exists in _________ states.

• 4

• 0

• 3

• 2

Multiple Choice

Question 25:-

At temperature below _______ Celsius, water freezes to form ice.

• 0 degree

• 34 degree

• 1 degree

• none of these

Multiple Choice

Question 26:-

______ is the process by which water becomes water vapour.

• Evaporation

• Condensation

• Precipitation

• Boiling

• Freezing

Multiple Choice

Question 27:-

Which controls the ecological functions of life?

• Water Cycle

• Water

• Bicycle

Exercise 2:-

​Fill in the Blanks with Suitable Answer:-

Exercise 3:-

True or False:-​

Multiple Choice

Question 33:-

Water is a good example for all states of matter.

• True

• False

Multiple Choice

Question 35:-

Water becoming water vapour on heating is called Condensation.

• True

• False

Multiple Choice

Question 37:-

Roof top harvesting method is used in agriculture field.

• False

• True

Draw

Question 38:-

Draw Anything that is Related to Water.

Open Ended

Question 39:-

What did you understand in this Lesson? How was It?

Open Ended

Question 40:-

How was your Experience in this Slide Lesson?