3 ARCHIVE GENERAL SCIENCE CLASS 3 (SEPTEMBER 2020 TO MARCH 2021)

           15 / MARCH / 2021           

 GENERAL SCIENCE 

REVISION

NOW WATCH THESE VIDEOS FOR BETTER UNDERSTANDING:

NATURAL RESOURCES ARE ALSO CALLED EARTH RESOURCES AS THEY ARE OBTAINED FROM VARIOUS COMPONENTS OF THE EARTH. THESE RESOURCES ARE GIFTS OF NATURE TO MANKIND.

EXAMPLES : WATER, AIR, MINERALS, OIL, SOIL AND SUNLIGHT.

LET US STUDY THESE RESOURCES AND FIND OUT EFFECTIVE MEASURES TO SAVE IT.

SOIL

SOIL IS THE UPPERMOST LAYER OF EARTH’S CRUST. SOIL IS FORMED BY THE FRICTION AND BREAKING UP OF ROCKS.

STRONG WINDS AND RIVER WATER CARRY AND DEPOSIT IT AT DIFFERENT PLACES.

IMPORTANCE OF SOIL

SOIL IS AN IMPORTANT NATURAL RESOURCE BECAUSE WE GROW GRAINS, VEGETABLES AND OTHER PLANTS ON IT. IT ALSO PROVIDES SHELTER TO A NUMBER OF INSECTS AND ANIMALS.

SOIL EROSION

THE PROCESS OF CARRYING AWAY OF SOIL BY WIND OR WATER IS CALLED SOIL EROSION.

HOW TO SAVE SOIL?

ROOTS OF THE TREES FIX THE SOIL PARTICLES TO GROUND AND HENCE CHECK EROSION. THEREFORE, MORE AND MORE TREES SHOULD BE PLANTED TO CHECK SOIL EROSION.

WATER

NEARLY 75% OF THE LAND IS COVERED WITH WATER WHICH IS PRESENT ON THE EARTH IN THE FORM OF VARIOUS BODIES LIKE PONDS, LAKES, RIVERS, SEAS AND OCEANS. IT IS ALSO PRESENT AS UNDERGROUND WATER.

IMPORTANCE OF WATER

• WE NEED WATER TO DRINK, BATHE, WASH,COOK AND CLEAN.

• WE ALSO NEED WATER TO IRRIGATE OUR CROPS.

WATER POLLUTION

THE PROCESS BY WHICH WATER GETS CONTAMINATED WITH SOLID WASTE, DEBRIS, AND OTHER HARMFUL SUBSTANCES IS CALLED WATER POLLUTION.

HOW TO SAVE WATER?

BASIC SAVING OF WATER STARTS AT HOME.

• CLOSE TAP WHEN NOT IN USE.

• DO NOT LEAVE THE TAP OPEN WHILE BRUSHING.

• DO NOT THROW ANY KIND OF WASTE INTO STAGNANT WATER.

• RAINWATER CAN BE COLLECTED IN CONTAINERS AND USED.

AIR

AIR IS A MIXTURE OF GASES. IT IS PRESENT IN THE LOWER LAYER OF ATMOSPHERE. MOVING AIR IS CALLED WIND AND IT POSSESSES A LOT OF ENERGY.

IMPORTANCE OF AIR

• ALL LIVING THINGS BREATHE IN AIR FOR THEIR SURVIVAL.

• GREEN PLANTS TAKE IN CARBON DIOXIDE PRESENT IN THE AIR TO PREPARE THEIR FOOD.

• ANIMALS TAKE IN OXYGEN FOR RESPIRATION.

• WIND IS USED TO RUN MILLS FOR GENERATING ENERGY.

AIR POLLUTION

THE PROCESS BY WHICH THE CLEAN AIR GETS CONTAMINATED WITH OTHER GASES, DUST AND CHEMICALS IS CALLED AIR POLLUTION.

HOW TO SAVE AIR FROM BEING POLLUTED?

• UNNECESSARY BURNING SHOULD BE DECREASED.

• TALL CHIMNEYS SHOULD BE PRESENT ON FACTORIES.

• MORE AND MORE TREES SHOULD BE PLANTED.

• USING POLLUTION FREE VEHICLES.

FOSSIL FUELS

THE REMAINS OF PLANTS AND ANIMALS WHICH WERE BURIED DEEP UNDER THE EARTH GOT CONVERTED INTO FOSSIL FUELS. THESE FUELS CONTAIN A LOT OF ENERGY. SOME OF THE FOSSIL FUELS ARE COAL, CHARCOAL, PETROL, DIESEL ETC.

IMPORTANCE OF FOSSIL FUELS

WE USE FOSSIL FUELS MAINLY TO GENERATE ENERGY. THIS ENERGY CAN BE USED FOR DOING ANY SORT OF WORK. DIFFERENT FUELS ARE USED FOR DIFFERENT PURPOSES.

1. COAL : TO RUN THE STEAM ENGINE.

2. PETROL : TO RUN VARIOUS VEHICLES.

3. KEROSENE : TO FILL IN LAMPS AND STOVES.

4. LPG : USED FOR COOKING.

HOW TO SAVE FUEL?

• COOKING ON A SLOW FLAME SAVES FUEL

• VEHICLES SHOULD BE KEPT IN PROPER CONDITIONS AS OLD AND DAMAGED VEHICLES CONSUME MORE FUEL.

• FOOD COOKED IN COVERED VESSEL EMPLOYS LESS FUEL.

• AVOID HEATING THE FOOD AGAIN AND AGAIN.

ASSIGNMENT: COMPLETE THE FOLLOWING IN YOUR SCIENCE-OCB

DO EX- A,B,C,D,E,F ON PAGE NO. 110 AND 111.

ANSWERS:-

A. TICK THE RIGHT OPTION:-

1. A) SOIL

2. B) ROOTS

3. A) CARBON DIOXIDE

4. B) KEROSENE

5. A) GASES

ANSWERS:-

B. FILL IN THE BLANKS:-

1. SHELTER, 2. TREES, 3. WATER POLLUTION, 4. HEATING, 5. VEHICLES.

ANSWERS:-

C. GIVE ONE WORD FOR THE FOLLOWING:-

1. NATURAL RESOURCES

2. SOIL

3. SOIL EROSION

4. WINDFARMS

5. AIR POLLUTION

D. NOISE POLLUTION, WATER POLLUTION, AIR POLLUTION.

ANSWERS:-

E. MATCH THE FOLLOWING:-

1- III

2 - IV

3 - I

4 - II

F. TRUE OR FALSE:-

1. TRUE, 2. FALSE, 3. TRUE, 4. TRUE, 5. TRUE.

           08 / MARCH / 2021           

 GENERAL SCIENCE 

REVISION

NOW WATCH THIS VIDEO FOR YOUR BETTER UNDERSTANDING:

WATER PLAYS A KEY ROLE IN CARRYING OUT IMPORTANT ACTIVITIES LIKE DRINKING, COOKING, BATHING, IRRIGATION ETC. HENCE, LIFE IS POSSIBLE ON THE EARTH DUE TO THE PRESENCE OF WATER. NEARLY THREE-FOURTH OF THE EARTH’S SURFACE IS COVERED WITH WATER. IT IS PRESENT IN ALL LIVING THINGS.

OCCURRENCE OF WATER

WATER IS PRESENT ALMOST IN ALL NATURAL THINGS LIKE PLANTS, ANIMALS, ROCKS AND AIR. IN THE SOLID STATE, IT EXISTS AS SNOW IN SNOW COVERED MOUNTAINS. IT IS PRESENT IN ROCKS AND MINERALS AS WATER OF CRYSTALLISATION AND AS WATER VAPOURS IN AIR.

SURFACE AND UNDERGROUND WATER

SURFACE WATER : WATER WHICH IS PRESENT ON THE SURFACE OF THE EARTH IS CALLED SURFACE WATER.

EXAMPLE : RAINWATER, SEA WATER.

UNDERGROUND WATER : THE WATER WHICH COLLECTS OVER THE HARD ROCK BELOW THE EARTH IS CALLED UNDERGROUND WATER.

EXAMPLE : WELL WATER, SPRING WATER.

WATER CYCLE

CIRCULATION OF WATER FROM THE EARTH’S SURFACE TO THE ATMOSPHERE AND BACK TO THE EARTH IS CALLED THE WATER CYCLE.

POTABLE WATER

WATER WHICH IS CLEAN AND PURE AND FIT FOR HUMAN CONSUMPTION IS KNOWN AS POTABLE WATER.

NEED FOR POTABLE WATER

THE WATER WHICH IS PRESENT IN LAKES, RIVERS AND AS UNDERGROUND WATER; CAN ONLY BE USED FOR HUMAN CONSUMPTION. THUS, THERE EXIST AN INTENSE NEED FOR POTABLE WATER.

CHARACTERISTICS OF DRINKING WATER :

IT SHOULD BE :

(I) COLOURLESS

(II) ODOURLESS

(III) FREE FROM SUSPENDED IMPURITIES

(IV) FREE FROM BACTERIA AND GERMS

(V) FREE FROM HARMFUL COMPOUNDS

PURIFICATION OF WATER

THE IMPURE WATER HAS TO UNDERGO SERIES OF STEPS FOR THE PROCESS OF PURIFICATION.

STEP I : PUMPING

WATER FROM RIVERS, LAKES IS FED INTO PUMPING STATION WHERE IT IS PUMPED INTO BIG RESERVOIRS.

STEP II : SEDIMENTATION

WATER IS COLLECTED IN RESERVOIRS. HEAVY PARTICLES SETTLE DOWN IN THIS TANK. CHEMICALS LIKE ALUM ARE ADDED TO SPEED THE PROCESS OF SEDIMENTATION.

STEP III : FILTRATION

AFTER SEDIMENTATION, THE WATER IS FILTERED THROUGH A CLEAN SANDBED TO REMOVE THE FINER SUSPENDED PARTICLES.

STEP IV : CHLORINATION

WATER IS THEN DISINFECTED WITH A VERY SMALL QUANTITY OF CHLORINE GAS TO KILL BACTERIA.

WATER PURIFICATION AT SMALL LEVEL

THE WATER BROUGHT TO THE HOUSES MAY SOMETIMES CARRY GERMS IN THE WAY. THESE GERMS MAY BE REMOVED BY:

BOILING AND STRAINING : WATER MAY BE BOILED AND THEN FILTERED WITH THE HELP OF A CLEAN CLOTH.

STORAGE : THE PURIFIED WATER SHOULD BE STORED IN CLEAN CONTAINERS WITH A LID.

CHLORINE TABLETS

CHLORINE TABLETS ARE USED TO KILL THE GERMS AT THE SMALL LEVEL. IT IS SIMPLY ADDED TO DRINKING WATER, THEN KEPT FOR SOMETIMES BEFORE CONSUMING.

HARD AND SOFT WATER

SOFT WATER : WATER WHICH FORMS LATHER WITH SOAP EASILY IS KNOWN AS SOFT WATER.

EXAMPLE : RAINWATER AND DISTILLED WATER.

HARD WATER : WATER WHICH DOES NOT FORM LATHER WITH SOAP IS KNOWN AS HARD WATER.

EXAMPLE : WELL WATER AND SPRING WATER.

WATER CONTAIN DISSOLVED GASES

• DISSOLVED GASES IN WATER PROVIDE TASTE TO THE WATER.

• OXYGEN DISSOLVED IN WATER HELPS IN THE RESPIRATION AND SURVIVAL OF AQUATIC LIFE.

• CARBON DIOXIDE DISSOLVED IN WATER HELPS IN PHOTOSYNTHESIS OF AQUATIC PLANTS.

SOLUBILITY AND SOLUTION

WATER IS KNOWN AS UNIVERSAL SOLVENT BECAUSE IT CAN DISSOLVE ALL KINDS OF SOLIDS, LIQUIDS OR GASES TO LITTLE OR MORE EXTENT. ACCORDING TO THE SOLUBILITY, THE SUBSTANCES MAY BE CLASSIFIED AS SOLUBLE OR INSOLUBLE SUBSTANCES.

• THE SUBSTANCES WHICH DISSOLVE RAPIDLY IN WATER ARE CALLED SOLUBLE SUBSTANCES.

EXAMPLES : COMMON SALT AND SUGAR.

• THE SUBSTANCES WHICH DISSOLVE VERY LITTLE OR DO NOT SEEM TO DISSOLVE ARE KNOWN AS INSOLUBLE SUBSTANCES.

EXAMPLES : MUD AND SAND.

SOLUTION

THE MIXTURE FORMED BY DISSOLVING A SOLUBLE SUBSTANCE IN WATER IS KNOWN AS SOLUTION.

COMMON TERMS USED IN THE FORMATION OF A SOLUTION

1. SOLVENT : A LIQUID WHICH DISSOLVES OTHER SUBSTANCES IN IT IS CALLED SOLVENT. FOR EXAMPLE, COMMON SALT DISSOLVES IN WATER

AND HENCE WATER IS A SOLVENT.

2. SOLUTE : A SUBSTANCE WHICH DISSOLVES IN A LIQUID IS CALLED SOLUTE. EXAMPLE : IN THE ABOVE EXAMPLE COMMON SALT IS THE

SOLUTE.

3. UNSATURATED SOLUTION : A SOLUTION WHICH HAS LESS AMOUNT OF SOLUTE IS KNOWN AS UNSATURATED SOLUTION.

4. SATURATED SOLUTION : A SOLUTION WHICH HAS LARGE AMOUNT OF SOLUTE IS KNOWN AS SATURATED SOLUTION.

CONDITIONS WHICH ENHANCE THE FORMATION OF A SOLUTION :

1. SOLUTE AND SOLVENT MUST BE CAPABLE OF MIXING.

2. HIGH TEMPERATURE ENHANCES THE FORMATION OF A SOLUTION.

3. STIRRING HELPS IN QUICK FORMATION OF THE SOLUTION.

4. SOLUTE SHOULD BE IN THE FORM OF A FINE POWDER, AS IT HELPS IN THE FORMATION OF SOLUTION QUICKLY.

IMPURITIES AND ITS REMOVAL

THERE ARE TWO TYPES OF IMPURITIES SOLUBLE AND INSOLUBLE.

BOTH THESE IMPURITIES ARE PRESENT IN WATER. THUS THE REMOVAL OF THESE IMPURITIES BECOME IMPORTANT.

SOME METHODS OF REMOVING INSOLUBLE IMPURITIES

1. FILTRATION THE SEPARATION OF INSOLUBLE IMPURITIES WITH THE HELP OF FILTER PAPER OR MUSLIN CLOTH IS KNOWN AS FILTRATION.

FILTRATE : THE CLEAR LIQUID WHICH PASSES THROUGH THE FILTER PAPER IS KNOWN AS FILTRATE.

RESIDUE : THE SOLID IMPURITY LEFT ON THE FILTER PAPER IS KNOWN AS RESIDUE.

2. SEDIMENTATION AND DECANTATION

THE PROCESS OF SETTLING DOWN OF HEAVY IMPURITIES IS KNOWN AS SEDIMENTATION AND THEN REMOVING THE CLEAR LIQUID FROM THE TOP IS KNOWN AS DECANTATION.

STEP I: THE IMPURE WATER IS ALLOWED TO STAND FOR SOMETIME.

STEP II: THE IMPURITIES SETTLE DOWN AT THE BOTTOM OF THE CONTAINER AS SEDIMENTS.

STEP III: THE CLEAN WATER POURED OUT INTO A SEPARATE CONTAINER IS KNOWN AS DECANTATION.

REMOVAL OF SOLUBLE IMPURITIES

SOLUBLE IMPURITIES ARE VERY FINELY MIXED IN WATER. HENCE, THEIR REMOVAL BECOMES BIT DIFFICULT. THESE IMPURITIES CAN BE REMOVED BY EVAPORATION OR BY DISTILLATION.

ASSIGNMENT: COMPLETE THE FOLLOWING IN YOUR SCIENCE-OCB

DO EX - A,B,C,D,E,F ON PAGE NO. 86 AND 87.

ANSWERS:-

A. TICK THE RIGHT ANSWER:-

1. B) RAIN WATER

2. A) CHLORINE

3. A) PUMPING

4. A) STRAINING

5. A) SOFT WATER

ANSWERS:-

B. FILL IN THE BLANKS:-

1. SOLUBLE, 2. SEDIMENTS, 3. FLOAT, 4. SATURATED, 5. OXYGEN.

ANSWERS:-

C. GIVE ONE WORD FOR THE FOLLOWING:-

1. UNDERGROUND WATER

2. WATER CYCLE

3. BOILING

4. MUSLIN CLOTH

D. BOILING, STRAINING

  STORAGE, STIRRING (CHLORINE TABLETS).

ANSWERS:-

E. MATCH THE FOLLOWING:-

1- III

2- II

3 - V

4 - I

5 - IV

F. TRUE OR FALSE:-

1. FALSE, 2. FALSE, 3. TRUE, 4. FALSE, 5. TRUE.

           04 / MARCH / 2021           

 GENERAL SCIENCE 

REVISION

ASSIGNMENT: COMPLETE THE FOLLOWING IN YOUR SCIENCE-OCB.

DO EX A, C,D, E,F ON PG NO. 72 TO 74.

ANSWERS:

A. TICK THE RIGHT OPTION:

1. A) BREAD

2. A) HYDROGEN GAS

3. A) SENSES

4. A) MOLECULES

5. A) THREE

ANSWERS:

B. FILL IN THE BLANKS:

1. PERCEIVED

2. INCREASES

3. MOLECULES

4. MATTER

5. GASEOUS

ANSWERS:

C. GIVE ONE WORD FOR THE FOLLOWING:

1.SOLID, 2. ATOM, 3. LIQUID, 4. HYDROGEN, 5. MOLECULES.

D. NAME THE FOLLOWING STATES:

A) SOLID, B) LIQUID, C) GAS

ANSWERS:

E. MATCH THE FOLLOWING:-

1. - IV

2. -  II

3. -  III

4. -  I

F. TRUE OR FALSE:

1. FALSE

2. TRUE

3. TRUE

4. TRUE

5. FALSE

           01 / MARCH / 2021           

 GENERAL SCIENCE 

NOW WATCH THE VIDEOS FOR YOUR BETTER UNDERSTANDING:

Whatever is present around us is known as matter. The table, chair, blackboard, chalk, duster, bags, air, water etc. can be called as matter.
• In other words we can see and feel matter by our senses.
• Matter is anything which occupies space, has weight and can be perceived by our senses.
A school bag containing books is a matter.

Composition of Matter
• Matter is just like a closed sac of grains.

• When it is opened, it gives you wheat grains which are like molecules.

• When it is grinded, it gives you small flour particles which are like atoms.

States of Matter

Solid State
• If molecules are present close to each other, then it is solid state.
• Solids have a definite shape.

Liquid State
• If molecules are present away from each other, then it is liquid state.
• Liquids take the shape of the container.

Gaseous State

• If molecules are present very far away from each other, then it is gaseous state.

• Gases do not have any definite shape.

Can states of matter be changed?
• When some solids are heated, they can change into a liquid or a gas.
• Some gases when cooled, change into liquids and solids.

ASSIGNMENT: READ CHAPTER 7 CAREFULLY AND COMPLETE PG NO.68 AND71 IN YOUR TEXT BOOK.

WORKSHEET- 1 PG NO. 68

ANSWERS:

1. WEIGHT, SPACE

2. A) TRUE ,B) FALSE, C) FALSE

3. MATTER, SPACE, PERCEIVED

4. D) ALL THE ABOVE.

5. 1) HYDROGEN GAS

   2) HYDROGEN GAS MAKES THE BALLOON LIGHT AND AND HENCE IT FLIES AWAY.

WORKSHEET 2 PG NO. 71.

ANSWERS:

1. SOLID, LIQUID, GAS

2. A) TRUE, B) FALSE, C) FALSE

3. SOLID

4. D) DO NOT HAVE A DEFINITE SHAPE.

5. A) SOLID B) LIQUID C) GAS.

           25 / FEBRUARY / 2021           

 GENERAL SCIENCE 

CHAPTER-  12 MEASUREMENT

ASSIGNMENT: COMPLETE THE FOLLOWING IN YOUR SCIENCE-OCB

DO EX A, B, C, D, E, F ON PAGE NO. 128 AND 129.

           11 / FEBRUARY / 2021           

 GENERAL SCIENCE 

CHAPTER-  11 MEASUREMENT

NOW WATCH THIS VIDEO FOR YOUR BETTER UNDERSTANDING:

WE ALL MAKE MEASUREMENTS IN OUR DAILY LIFE. WHETHER WE ARE IN A FACTORY, SHOP OR AT HOME.

• MEASUREMENT IS ONE OF THE MOST USEFUL PROCESSES IN SCIENCE AND IN OUR DAILY LIFE.

• IT IS DONE WITH THE HELP OF SOME STANDARD VALUE.

WHENEVER YOU WANT TO GET YOUR DRESSES STITCHED, THE TAILOR TAKES YOU MEASUREMENT.

UNIT

A UNIT IS DEFINED AS A FIXED QUANTITY USED AS A STANDARD OF MEASUREMENT.

MEASUREMENT OF LENGTH

IN OUR DAY TO DAY WORK, WE USE A SCALE TO MEASURE SMALL LENGTHS, E.G., A LINE DRAWN ON A NOTEBOOK.

WHEN YOU GO TO THE MARKET TO BUY CLOTHES WITH YOUR MOTHER, YOU ASK FOR CLOTH IN METRES. THE CLOTH MERCHANT MEASURES IT WITH THE HELP OF A METRE SCALE, E.G., 4 M OF CLOTHES (M = METRES).

• FOR RELATIVELY BIGGER DISTANCES, WE USE KILOMETRES AS THE UNIT.

EXAMPLE : DISTANCE BETWEEN JALANDHAR AND AMRITSAR IS 80 KM (KM =KILOMETRES)

CONCLUSION :

MEASUREMENT OF WEIGHT

WHEN YOU BUY FRUITS AND VEGETABLES, THE SHOPKEEPER MEASURES THE QUANTITY. THIS IS MEASUREMENT OF MASS. MOST OF THE THINGS WE PURCHASE FROM MARKET ARE MEASURED BY THEIR QUANTITY.

WHEN A VERY SMALL QUANTITY OF A SUBSTANCE HAS TO BE PURCHASED, THEN WE USE GRAMS. FOR EXAMPLE, WHEN WE GO TO BUY GOLD, WE ASK FOR GOLD IN GRAMS. HE USES A  SMALL PHYSICAL BALANCE TO WEIGH THIS SMALL PIECE OF GOLD.

• RELATIVELY LARGER QUANTITIES ARE MEASURED IN KILOGRAMS (KG).

EXAMPLE : WHENEVER WE BUY FRUITS, VEGETABLES, PULSES, FLOUR ETC., WE BUY IT IN KILOGRAMS.

MEASUREMENT OF TIME

WE ALL GET UP IN THE MORNING. YOU GET READY AND GO TO SCHOOL. AT WHAT TIME SHOULD YOU GET UP? HOW LONG DO YOU TAKE TO GET READY? THESE QUESTIONS ARE RELATED TO MEASUREMENT OF TIME.

THE DEVICES USED TO MEASURE TIME ARE WATCH AND CLOCK.

• SMALLER UNIT OF TIME IS SECOND, LARGER IS MINUTE AND THE ONE STILL LARGER IS HOUR

• DAY, MONTH AND YEAR ARE ALSO CONSIDERED AS LARGER UNITS OF TIME.

1 HOUR = 60 MINUTES

1 MINUTE = 60 SECONDS

MEASUREMENT OF TEMPERATURE

TEMPERATURE IS DEFINED AS THE DEGREE OF HOTNESS OR COLDNESS OF A BODY.

WE USE THERMOMETER TO MEASURE THE TEMPERATURE.

OUR BODY TEMPERATURE IS MEASURED BY DOCTOR OR AT HOME WITH THE HELP OF CLINICAL THERMOMETER.

TEMPERATURE OF BOILING WATER ETC. IS MEASURED WITH THE HELP OF A LABORATORY THERMOMETER.

ASSIGNMENT: READ CHAPTER 12 CAREFULLY AND DO WORKSHEET 1 AND 2 ON PAGE NO.125 AND 127.

           08 / FEBRUARY / 2021           

 GENERAL SCIENCE 

CHAPTER-  11 SOUND AND NOISE

ASSIGNMENT: COMPLETE THE FOLLOWING IN YOUR SCIENCE-OCB.

DO EX- A,B,C,D,E,F ON PAGE NO. 119,120.

           04 / FEBRUARY / 2021           

 GENERAL SCIENCE 

CHAPTER-  11 SOUND AND NOISE

Now watch this video for your better understanding: 

Sound is the sensation of hearing. It is produced when something vibrates.

When we speak our tongue vibrates and sound is produced.

We hear different sounds everyday. The chirping of birds, rattling of leaves and thunder are natural sounds. The ringing of the door bell, blowing of horns and the sounds produced by machines are all artificial sounds.

Types of Sounds

In our daily lives we come across different types of sounds. Some are soft, some are loud; some are pleasant and some are unpleasant. Some sounds are shrill and some are flat.

Sounds produced by living things :

Plants

• Plants produce sound by rattling of their leaves when air blows.

• When twigs, branches and fruits fall down from the leaves.

• When animals and birds make their way through the leaves and branches.

Animals

Animals make variable sounds. Few examples are buzzing of bees; chirping of birds ;  hissing of snakes and mooing of cows.

TYPES OF SOUNDS

1. Soft and Loud

2. Pleasant and Unpleasant

3. Shrill and Flat

NOISE

Sound which is loud and unpleasant is called noise. Noise produce strong vibrations which can cause damage to our ear drums. Very loud sounds sometimes cause permanent deafness.

Steps to reduce noise pollution :

Following measures should be taken to reduce noise pollution :

1. We should not play the television, radio or music player at loud volumes.

2. Try to blow horns only when necessary.

3. Loud speakers should be avoided.

4. DJ should be used only for a limited period of time.

Assignment:

Read Chapter 11 carefully and Do Worksheet 1 and 2 on page No. 116 and 118.

           01 / FEBRUARY / 2021           

 GENERAL SCIENCE 

CHAPTER-  10 SAVE NATURAL RESOURCES

Assignment: Do the following in your Science- OCB.

Do Exs A,B,C, D,E,F on page No. 110,111.

A. Tick the right option :

1. The uppermost layer of earth's crust is

a) soil  b) water

2. What fixes the soil particles to ground

a) stem  b) roots

3. Plants prepare their food with the help of

a) carbon dioxide  b) oxygen

4. Stoves burn with the help of

a) petrol  b) kerosene

5. Air is a mixture of

a) gases  b) liquids

B. Fill in the blanks with the given options:

vehicles, water pollution, shelter, trees, heating.

1. Soil provides _______ to number of insects and animals.

2. More_______ should be planted to check soil erosion.

3. Waste thrown in water becomes a major cause of __________.

4. Avoid _______ the food again and again.

5. Petrol is used to run various _______.

C.Give one word for the following:

1. Resources provided by nature.

  N ____________.

2. Upper most layer of earth's crust

  S_______.

3. Process of carrying away of soil

  S____________.

4. Where wind is used to generate electricity

  W________.

5. Contamination of air by other gases and chemicals.

  A__________.

           28 / JANUARY / 2021           

 GENERAL SCIENCE 

CHAPTER-  10 SAVE NATURAL RESOURCES

Now watch this video for better understanding:

 

Natural resources are also called earth resources as they are obtained from various components of the earth. These resources are gifts of nature to mankind.

Examples : Water, air, minerals, oil, soil and sunlight.

Let us study these resources and find out effective measures to save it.

SOIL
Soil is the uppermost layer of earth’s crust. Soil is formed by the friction and breaking up of rocks.

Strong winds and river water carry and deposit it at different places.

Importance of Soil
Soil is an important natural resource because we grow grains, vegetables and other plants on it. It also provides shelter to a number of insects and animals.

Soil Erosion

The process of carrying away of soil by wind or water is called soil erosion.

How to save soil?
Roots of the trees fix the soil particles to ground and hence check erosion. Therefore, more and more trees should be planted to check soil erosion.

WATER
Nearly 75% of the land is covered with water which is present on the earth in the form of various bodies like ponds, lakes, rivers, seas and oceans. It is also present as underground water.

Importance of water
• We need water to drink, bathe, wash,cook and clean.
• We also need water to irrigate our crops.

Water Pollution
The process by which water gets contaminated with solid waste, debris, and other harmful substances is called water pollution.

How to save water?
Basic saving of water starts at home.
• Close tap when not in use.
• Do not leave the tap open while brushing.
• Do not throw any kind of waste into stagnant water.
• Rainwater can be collected in containers and used.

AIR
Air is a mixture of gases. It is present in the lower layer of atmosphere. Moving air is called wind and it possesses a lot of energy.

Importance of Air
• All living things breathe in air for their survival.
• Green plants take in carbon dioxide present in the air to prepare their food.

• Animals take in oxygen for respiration.

• Wind is used to run mills for generating energy.

Air Pollution
The process by which the clean air gets contaminated with other gases, dust and chemicals is called air pollution.

How to Save Air from Being Polluted?
• Unnecessary burning should be decreased.
• Tall chimneys should be present on factories.
• More and more trees should be planted.
• Using pollution free vehicles.

FOSSIL FUELS
The remains of plants and animals which were buried deep under the earth got converted into fossil fuels. These fuels contain a lot of energy. Some of the fossil fuels are coal, charcoal, petrol, diesel etc.

Importance of Fossil Fuels
We use fossil fuels mainly to generate energy. This energy can be used for doing any sort of work. Different fuels are used for different purposes.

1. Coal : To run the steam engine.

2. Petrol : To run various vehicles.

3. Kerosene : To fill in lamps and stoves.

4. LPG : Used for cooking.

How To Save Fuel?
• Cooking on a slow flame saves fuel
• Vehicles should be kept in proper conditions as old and damaged vehicles consume more fuel.
• Food cooked in covered vessel employs less fuel.
• Avoid heating the food again and again.

Assignment: Read Chapter 10 carefully and Do Worksheet 1 and 2 on page No.106,109 in the text book.

           25 / JANUARY / 2021           

 GENERAL SCIENCE 

CHAPTER-  8 WATER

Assignment : Complete the following in  yourScience-OCB .

Do Ex A,B,C,D,E,F on page No.86,87.

A. Tick the right choice:

1. Which of the following is pure form of water?

a) surface water b) rainwater

2. Which gas is used to disinfectant water?

a) chlorine b) bromine

3. When water from rivers is fed into big reservoirs. The process is 

a) pumping b) sending

4. The process of filtration with the help ofmuslin cloth is

a) straining b) removing

5. Water which forms lather with soap easily is known as:

a) soft water b) hard water

B. Fill in the blanks with the given options:

Saturated, Oxygen, Soluble, float,sediments

1. ______ impurities are very finely mixed in water. 

 2. The impurities settle down at the bottom of the container are ______.

3. Lighter substances _______ in water.

4. Excess of salt present in ______ solution.

5. ________ gas helps in the respiration.

           21 / JANUARY / 2021           

 GENERAL SCIENCE 

CHAPTER-  8 WATER

Now watch these videos for better understanding:

 

 

Water plays a key role in carrying out important activities like drinking, cooking, bathing, irrigation etc. Hence, life is possible on the earth due to the presence of water. Nearly three-fourth of the earth’s surface is covered with water. It is present in all living things.

OCCURRENCE OF WATER

Water is present almost in all natural things like plants, animals, rocks and air. In the solid state, it exists as snow in snow covered mountains. It is present in rocks and minerals as water of crystallisation and as water vapours in air.

Surface and underground water

Surface water : Water which is present on the surface of the earth is called surface water.

Example : Rainwater, sea water.

Underground water : The water which collects over the hard rock below the earth is called underground water.

Example : Well water, spring water.

WATER CYCLE
Circulation of water from the earth’s surface to the atmosphere and back to the earth is called the water cycle.

POTABLE WATER
Water which is clean and pure and fit for human consumption is known as potable water.

Need for Potable Water
The water which is present in lakes, rivers and as underground water; can only be used for human consumption. Thus, there exist an intense need for potable water.

Characteristics of Drinking Water :
It should be :
(i) Colourless
(ii) Odourless
(iii) Free from suspended impurities
(iv) Free from bacteria and germs
(v) Free from harmful compounds

PURIFICATION OF WATER
The impure water has to undergo series of steps for the process of purification.

Step I : Pumping
Water from rivers, lakes is fed into pumping station where it is pumped into big reservoirs.

Step II : Sedimentation
Water is collected in reservoirs. Heavy particles settle down in this tank. Chemicals like alum are added to speed the process of sedimentation.

Step III : Filtration
After sedimentation, the water is filtered through a clean sandbed to remove the finer suspended particles.

Step IV : Chlorination
Water is then disinfected with a very small quantity of chlorine gas to kill bacteria.

Water Purification at Small level
The water brought to the houses may sometimes carry germs in the way. These germs may be removed by:

Boiling and Straining : Water may be boiled and then filtered with the help of a clean cloth.

Storage : The purified water should be stored in clean containers with a lid.

Chlorine Tablets
Chlorine tablets are used to kill the germs at the small level. It is simply added to drinking water, then kept for sometimes before consuming.

Hard and Soft Water

Soft Water : Water which forms lather with soap easily is known as soft water.

Example : Rainwater and distilled water.

Hard Water : Water which does not form lather with soap is known as hard water.

Example : Well water and spring water.

Water Contain Dissolved Gases
• Dissolved gases in water provide taste to the water.

• Oxygen dissolved in water helps in the respiration and survival of aquatic life.

• Carbon dioxide dissolved in water helps in photosynthesis of aquatic plants.

SOLUBILITY AND SOLUTION
Water is known as universal solvent because it can dissolve all kinds of solids, liquids or gases to little or more extent. According to the solubility, the substances may be classified as soluble or insoluble substances.
• The substances which dissolve rapidly in water are called soluble substances.

Examples : Common salt and sugar.

• The substances which dissolve very little or do not seem to dissolve are known as insoluble substances.

Examples : Mud and sand.

SOLUTION
The mixture formed by dissolving a soluble substance in water is known as solution.

Common Terms used in the formation of a Solution
1. Solvent : A liquid which dissolves other substances in it is called solvent. For example, common salt dissolves in water
and hence water is a solvent.

2. Solute : A substance which dissolves in a liquid is called solute. Example : In the above example common salt is the
solute.

3. Unsaturated Solution : A solution which has less amount of solute is known as unsaturated solution.

4. Saturated Solution : A solution which has large amount of solute is known as saturated solution.

Conditions which enhance the formation of a solution :
1. Solute and solvent must be capable of mixing.
2. High temperature enhances the formation of a solution.
3. Stirring helps in quick formation of the solution.
4. Solute should be in the form of a fine powder, as it helps in the formation of solution quickly.

IMPURITIES AND ITS REMOVAL
There are two types of impurities soluble and insoluble.

Both these impurities are present in water. Thus the removal of these impurities become important.

Some methods of removing insoluble impurities
1. Filtration The separation of insoluble impurities with the help of filter paper or muslin cloth is known as filtration.
Filtrate : The clear liquid which passes through the filter paper is known as filtrate.
Residue : The solid impurity left on the filter paper is known as residue.

2. Sedimentation and Decantation
The process of settling down of heavy impurities is known as sedimentation and then removing the clear liquid from the top is known as decantation.

Step I: The impure water is allowed to stand for sometime.

Step II: The impurities settle down at the bottom of the container as sediments.

Step III: The clean water poured out into a separate container is known as decantation.

Removal of soluble impurities
Soluble impurities are very finely mixed in water. Hence, their removal becomes bit difficult. These impurities can be removed by evaporation or by distillation.

Assignment: Read Chapter 8 and Do Worksheet - 1,2,3 on page No. 80,83 and 85 in the text book.

           18 / JANUARY / 2021           

 GENERAL SCIENCE 

CHAPTER-  7 States of Matter

Assignment: Do the following in your Science- OCB.

Do Ex A,B,C,D,E,F on page No. 72,73,74.

           11 / JANUARY / 2021           

 GENERAL SCIENCE 

CHAPTER-  7 States of Matter

Now watch these videos for your better understanding: 

 

Whatever is present around us is known as matter. The table, chair, blackboard, chalk, duster, bags, air, water etc. can be called as matter.

• In other words we can see and feel matter by our senses.

• Matter is anything which occupies space, has weight and can be perceived by our senses.

A school bag containing books is a matter.

Composition of Matter
• Matter is just like a closed sac of grains.

• When it is opened, it gives you wheat grains which are like molecules.

• When it is grinded, it gives you small flour particles which are like atoms.

States of Matter

Solid State
• If molecules are present close to each other, then it is solid state.
• Solids have a definite shape.

Liquid State
• If molecules are present away from each other, then it is liquid state.
• Liquids take the shape of the container.

Gaseous State
• If molecules are present very far away from each other, then it is gaseous state.
• Gases do not have any definite shape.

Can states of matter be changed?
• When some solids are heated, they can change into a liquid or a gas.
• Some gases when cooled, change into liquids and solids.

Assignment: Read Chapter 7 carefully and Do Pg No. 68 and 71 in the text book.

           10 / DECEMBER / 2020           

 GENERAL SCIENCE 

CHAPTER-  5 Birds and their claws

(Revision)

Assignment: Complete the following in your Science- OCB.

Do  Exs. A ,B,C,D,E,F on page No. 53 and 54.
A. Tick the right option:
1. The laziest bird is:
a) Crow  b) Koel
2. Which bird use sticks to make big nests?
a) Eagle be) Vulture
3. Which bird see big leaves together?
a) Tailor bird  b) Koel
4. Which animal make a nest every night?
a) Gorilla  b) Monkey
5. The smallest bird is:
a) Hummingbird    b) Sparrow

B. Fill in the blanks with the given options below:
enemies, webbed, ostrich, kiwi, peacock

1. Largest egg belongs to ________.
2. National bird of New Zealand is ________.
3. ________ is the national bird of lndia.
4. Swimming birds have _______ feet.
5. The feet and claws protect birds from their _______.

C. Give one word for the following.
1. Bird with two toes pointing upwards and two downwards
P ___________.
2. Claws of preying birds are called
T___________.
3. National bird of lndia
P ________.
4. Type of feet possessed by duck
W _________.
5. Bird which use hole as a nest
W ___________.

F. Write True or False:
1. Hummingbird is the smallest bird.
2. Kiwi have nostrils at the end of their beaks.
3. Kiwi and Penguin can fly very fast.
4. Ducks are known as perching birds.
5. Cranes scratch in mud for insects.

Do this activity and fun file on page No. 55

Activity: Write all the birds name that you can see in the picture.

           07 / DECEMBER / 2020           

 GENERAL SCIENCE 

CHAPTER-  5 Birds and their claws

(Revision)

How do we walk? We have feet to stand and to walk. The birds normally fly but sometimes they stand on their claws to eat grains or the food stuff they like. They hold the branches with their claws and even protect themselves with their claws.

The claws of birds help them in number of ways :

• Help the birds to hold the branch.

• Help the birds to hold their prey.

• Help the birds to climb up the trees.

• Help the birds to walk and run on ground.

• Help the birds to scratch for seeds and worms.

Different birds have different types of claws. It actually depends on the functions which a bird has to perform. The functions can vary with food habits, type of nests it makes and the type of locomotion or movement. The main function of feet and claws is protecting themselves from their enemies and moving about. Depending upon the structure of claws, the birds can be classified as:

• Perching birds

• Scratching birds

• Climbing birds

• Wading birds

• Preying birds

• Swimming birds

1. Perching Birds
Birds like crow, sparrow etc. perch and hop on the branches. They have three toes in front and one at the back. Such toes help them to hold the branches firmly.

They hop on the ground and can even sleep while perching.

2. Climbing Birds
Birds like woodpecker and parrots have two toes pointing upwards and two downwards. Such toes help them to climb up the trees.

3. Preying Birds
Birds like eagles, hawks etc. have strong and sharp claws to catch and hold their prey. The claws of preying birds are called talons.

4. Scratching Birds
Birds like hens use their claws to scratch the earth for seeds and worms. Such birds are called scratching birds. They have sharp and hard claws with three toes in front and one at the back. These birds can both walk and run on the ground.

5. Wading Birds
Birds like cranes, herons walk in shallow water especially in search of food. Such birds are called wading birds. These birds have long legs and wide spreading toes. These toes keep the feet from sinking in the soft mud.

6. Swimming Birds or Aquatic Birds
Birds like ducks and swans swim in water. Such birds are called swimming or aquatic birds. These birds have webbed feet. These feet help them to paddle and push water while swimming.

NESTS OF BIRDS
As we all live in a house. Birds live in a nest. Nest is the dwelling place of a bird. They build their nest to lay eggs, keep their young ones safe and warm.

Different birds have different type of nests. The nests differ in the shape, size and nature of material used for building the nest.

• Bulbul’s Nest
Bulbuls build their nests in hedges and bushes with the help of grass. The nests look like a deep cup.

• Tailor Bird’s Nest
A weaver bird uses its beak to sew big leaves together with the help of thread, wool etc., to make a cosy nest.

• Woodpecker’s Nest
Woodpecker makes a hole into the trunk  of a tree. This hole is used as a nest.

• Vulture’s Nest
Vultures use sticks to make big nests in tall trees.

• Owl’s Nest
Owls make their nest in the hollow of a tree. The nest is lined with feathers and grass.

Assignment: Read Chapter 5 carefully and Do Pg No. 49 and 52 in the text book.

           26 / NOVEMBER / 2020           

 GENERAL SCIENCE 

CHAPTER-  12  MEASUREMENT

Assignment: Do the following in your Science- OCB.

Do Ex A,B,C,D,E,F on page No.128 and 129.

A. Tick the right option:

1. Line drawn in your notebook is measured with the help of

a) scale  b) metre rod.

2. Unit used to measure quantity of vegetable is 

a) Kilometre b) Kilogram

3. Which is the bigger unit of time?

a) minute b) hours

4. Weight is measured by

a) balance b) watch

5. Thermometer measures

a) time b) temperature

B. Fill in the blanks with  given options:

Unit, measurement, goldsmith, clinical thermometer,kilograms.

1. ________ measures temperature of your body.

2. __________ sells gold.

3. A tailor takes your _______ to stitch your dress.

4. Measurement is taken with the help of ___________.

5. My friend weighs 50_______.

           23 / NOVEMBER / 2020           

 GENERAL SCIENCE 

CHAPTER-  12  MEASUREMENT

Now watch this video for better understanding:

We all make measurements in our daily life. Whether we are in a factory, shop or at home.
• Measurement is one of the most useful processes in science and in our daily life.
• It is done with the help of some standard value.

Whenever you want to get your dresses stitched, the tailor takes you measurement.

Unit

A unit is defined as a fixed quantity used as a standard of measurement.

Measurement of Length

In our day to day work, we use a scale to measure small lengths, e.g., a line drawn on a notebook.

When you go to the market to buy clothes with your mother, you ask for cloth in metres. The cloth merchant measures it with the help of a metre scale, e.g., 4 m of clothes (m = metres).

• For relatively bigger distances, we use kilometres as the unit.

Example : Distance between Jalandhar and Amritsar is 80 km (km =kilometres)

Conclusion :

Measurement of Weight

When you buy fruits and vegetables, the shopkeeper measures the quantity. This is measurement of mass. Most of the things we purchase from market are measured by their quantity.

When a very small quantity of a substance has to be purchased, then we use grams. For example, when we go to buy gold, we ask for gold in grams. He uses a  small physical balance to weigh this small piece of gold.

• Relatively larger quantities are measured in kilograms (kg).

Example : Whenever we buy fruits, vegetables, pulses, flour etc., we buy it in kilograms.

Measurement of Time

We all get up in the morning. You get ready and go to school. At what time should you get up? How long do you take to get ready? These questions are related to measurement of time.

The devices used to measure time are watch and clock.

• Smaller unit of time is second, larger is minute and the one still larger is hour

• Day, month and year are also considered as larger units of time.

1 hour = 60 minutes

1 minute = 60 seconds

Measurement of Temperature

Temperature is defined as the degree of hotness or coldness of a body.

We use thermometer to measure the temperature.
Our body temperature is measured by doctor or at home with the help of clinical thermometer.

Temperature of boiling water etc. is measured with the help of a laboratory thermometer.

Assignment:

Read chapter 12 carefully and Do Pg No.  125,127 in the text book.

           12 / NOVEMBER / 2020           

 GENERAL SCIENCE 

CHAPTER- 4 Birds and their beaks

(Revision)

BEAKS OF BIRDS

Now watch this video for better understanding:

As we have mouth to eat, birds have beaks. The beak of bird is designed according to the food it eats. Thus, the shape of beak vary from bird to bird. Some birds use their beak to protect themselves from their enemies.

Types of Beaks

1. Small, hard and pointed beaks :

Birds like sparrow and pigeon which eat grains, seed and crack nuts have small, hard and pointed beaks.

2. Curved beaks :

Birds like parakeet have curved beak. This curved beak helps it to crack nuts and hard fruits. It also helps a parakeet to climb.

3. Strong, sharp and hooked beaks :

Birds like eagles, vultures, kites, owls and hawks have strong, sharp and hooked beaks for tearing the flesh of small birds.

4. Broad and flat beak :

Birds like ducks have broad and flat beaks. Such beaks help them to dig in soft mud and find worms for its food.

5. Strong and chisel-shaped beak :

Birds like woodpecker have strong and chisel shaped beak. It helps the woodpecker to make holes in tree trunk and catch insects for its food.

6. Broad and short beak :

Birds like swallow have broad and short beak. Its beak is sticky from inside. It has a very different way of feeding. It moves round and round in air with its beak open. Tiny flying insects get struck inside their beaks.

7. Broad, long and pointed beak :

Birds like kingfisher and storks have broad, long and pointed beaks to catch fish from rivers and ponds.

Assignment: Study chapter 4 carefully and complete all Ex in your Science- OCB.

           09 / NOVEMBER / 2020           

 GENERAL SCIENCE 

CHAPTER- 4 Birds and their beaks

(Revision)

Now watch this video for better understanding:

Birds are beautiful creatures different from plants and animals. They are the animals with feathers. There are about 8600 species of birds.

Birds have light bodies. They have well formed wings attached to their body with the help of strong muscles. A bird flaps its wings in both directions i.e., upward and downward direction to fly.

The upward movement of wings is known as upstroke.

The downward movement of wings is known as downstroke.

FEATHERS

A bird’s body is covered with feathers. Each bird has different kinds of feathers.

1. Body feathers : Feathers which are small and of different colours and cover the body of birds are known as body feathers.

2. Down feathers : Down feathers are fluffy and soft. They keep the bird warm.

3. Flight feathers : Flight feathers are long and found mainly on the wings. They help the bird to fly.

All BIRDS CANNOT FLY

Some birds like ostrich and penguin cannot fly because they are too heavy to fly.

Aquatic Birds

Some birds can swim in water. Such birds are known as aquatic birds.

Features of Aquatic Birds

Aquatic birds have:

1. Oil-glands which keep their feathers water proof.

2. They have webbed feet which help them to swim in water.

Birds help in dispersal of seeds. They support out ecosystem and helps it to function smoothly.

Assignment: Do the following in your Science- OCB.

Do Ex - D,E,F on page No. 120

           05 / NOVEMBER / 2020           

 GENERAL SCIENCE 

CHAPTER-  11 SOUND AND NOISE

Now watch this video for better understanding:

TYPES OF SOUNDS

1. Soft and Loud

2. Pleasant and Unpleasant

3. Shrill and Flat

NOISE

Now watch this video for better understanding:

Sound which is loud and unpleasant is called noise. Noise produce strong vibrations which can cause damage to our ear drums. Very loud sounds sometimes cause permanent deafness.

Steps to reduce noise pollution :

Following measures should be taken to reduce noise pollution :

1. We should not play the television, radio or music player at loud volumes.

2. Try to blow horns only when necessary.

3. Loud speakers should be avoided.

4. DJ should be used only for a limited period of time.

Assignment: Do the following in your Science- OCB.

Do Ex No. A,B,C on page No.119 and 120.

           02 / NOVEMBER / 2020           

 GENERAL SCIENCE 

CHAPTER-  11 SOUND AND NOISE

Now watch this video for better understanding:

Sound is the sensation of hearing. It is produced when something vibrates.

When we speak our tongue vibrates and sound is produced.

We hear different sounds everyday. The chirping of birds, rattling of leaves and thunder are natural sounds. The ringing of door bell, blowing of horns and the sounds produced by machines are all artificial sounds.

Types of Sounds
In our daily lives we come across different types of sounds. Some are soft some are loud; some are pleasant and some are unpleasant. Some sounds are shrill and some are flat.

Sounds produced by living things :
Plants
• Plants produce sound by rattling of their leaves when air blows.
• When twigs, branches and fruits fall down from the leaves.
• When animals and birds make their way through the leaves and branches.

Animals
Animals make variable sounds. Few examples are buzzing of bees; chirping of birds ;  hissing of snakes and mooing of cows.

Assignment:

Read Pg No. 114 and 115 carefully and Do Pg No. 116 in the text book.

           29 / OCTOBER / 2020           

 GENERAL SCIENCE 

CHAPTER-  3  PLANTS

(Revision)

LEAF

Leaves are usually green coloured structures attached to the stem. The leaf absorbs maximum sunlight due to its flat surface.

Functions of Leaves
• Green leaves help the plant to prepare its food.
• Leaves contain stomata. It helps the leaves to breathe.

• Some leaves become thick and fleshy and store food. Such leaves can be used for eating.

FLOWERS

Flowers are the colourful structures attached to the stem. They make the plant look attractive.

Functions of Flowers
• Flowers help in the reproduction of plants.
• Many flowers like rose and jasmine yield perfumes.
• Many flowers produce a sweet liquid called nectar.
• Some flowers change into fruit.

FRUITS

Fruits are the sweet edible part of a plant. Fruits also contain a sweet fragrance. Not only human beings but many birds and animals also eat fruits. Fruits are formed from flowers. They contain seeds.

The number of seeds are different in different fruits.

Functions of Fruits
• Fruits store food material.
• Fruit contain the seeds which when sown give rise to a new plant.
Seeds

Seeds are the hard structures present in a fruit. Seed contain a tiny baby plant in it. This baby plant in the seed is protected by a seed coat.

Types of Seeds

Edible seeds: Seeds of some plants can be eaten. Such seeds are called edible seeds. e.g., Wheat and gram.

Non-edible seeds: Seeds of some plants cannot be eaten. Such seeds are called non-edible seeds. e.g., Orange and apple seeds. Seed is protected by a hard layer. When it is sown, the seed coat burst open and a baby plant emerges out. This baby plant grows into a healthy plant on receiving proper amount of sunlight, air, water and minerals from soil.

Assignment: Do the following in your Science- OCB.

Do Exs D,E,F on page No. 110 and 111.

           19 / OCTOBER / 2020           

 GENERAL SCIENCE 

CHAPTER-  3  PLANTS

(Revision)

Now watch this video to help you understand better.

Plants are living organisms. They are fixed to the soil. Plants also have many body parts. There are different kinds of plants. These plants differ in height, structure and looks. Most of the plants grow in soil. Hence, we can divide the body of a plant into two main parts : root and shoot.

Similarly, the different parts of a plant perform different functions. Each plant part has an important task to do in the life of the plant.

Roots fix the plants to the soil and shoots contain stems which bears fruits, flowers and buds.

ROOT
The part of the plant which remains under the ground is called the root.

Functions of Roots
• It holds the plant firmly to the soil.
• It helps to take up water and minerals from the soil.
• Some roots store the food and are used for eating.

Types of Roots
Roots are mainly of two types:
• Fibrous roots
• Tap roots

Fibrous Root System— When several tiny roots grow from the end of the stem, it is called fibrous root system.

Examples : Wheat and Rice.

Tap Root System— When a single main root grows from the end of the stem and many small roots grow from it, it is called a tap root system.

Examples : Cotton and Mustard.

STEM

Stem is the main part of the shoot. It bears leaves, buds and flowers. The main stem which is large and thick is called the trunk and the other thinner stems are called branches.

Functions of the Stem
• The stem holds up leaves and flowers.
• It carries water to all parts of the plant.
• Hard stems support the plant.
• Weak and green stems prepare food for the plant.
• Some stems store the food and are used for eating.

Types of Stems
Stem is broadly classified into three categories:

Assignment: Do the following in your Science- OCB.

Do Exs A,B,C on page No. 110.

A. Tick the right option :

1. The uppermost layer of the earth's crust is

a) soil  b) water

2. What fixes the soil particles to the ground

a) stem  b) roots

3. Plants prepare their food with the help of

a) carbon dioxide  b) oxygen

4. Stoves burn with the help of

a) petrol  b) kerosene

5. Air is a mixture of

a) gases  b) liquids

B. Fill in the blanks with the given options:

vehicles, water pollution, shelter, trees, heating.

1. Soil provides _______ to a number of insects and animals.

2. More_______ should be planted to check soil erosion.

3. Waste thrown in water becomes a major cause of __________.

4. Avoid _______ the food again and again.

5. Petrol is used to run various _______.

C. Give one word for the following:

1. Resources provided by nature.

  N ____________.

2. Upper most layer of earth's crust

  S_______.

3. Process of carrying away of soil

  S____________.

4. Where wind is used to generate electricity

  W________.

5. Contamination of air by other gases and chemicals.

  A__________.

           15 / OCTOBER / 2020           

 GENERAL SCIENCE 

CHAPTER- 10 SAVE NATURAL RESOURCES. 

Now watch this video to help you understand better.

Natural resources are also called earth resources as they are obtained from various components of the earth. These resources are gifts of nature to mankind.

Examples : Water, air, minerals, oil, soil and sunlight.

Let us study these resources and find out effective measures to save it.

SOIL
Soil is the uppermost layer of the earth’s crust. Soil is formed by the friction and breaking up of rocks.

Strong winds and river water carry and deposit it at different places.

Importance of Soil
Soil is an important natural resource because we grow grains, vegetables and other plants on it. It also provides shelter to a number of insects and animals.

Soil Erosion
The process of carrying away of soil by wind or water is called soil erosion.

How to save soil?

Roots of the trees fix the soil particles to the ground and hence check erosion. Therefore, more and more trees should be planted to check soil erosion.

WATER

Nearly 75% of the land is covered with water which is present on the earth in the form of various bodies like ponds, lakes, rivers, seas and oceans. It is also present as underground water.

Importance of water
• We need water to drink, bathe, wash, cook and clean.
• We also need water to irrigate our crops.

Water Pollution
The process by which water gets contaminated with solid waste, debris, and other harmful substances is called water pollution.

How to save water?
Basic saving of water starts at home.
• Close the tap when not in use.
• Do not leave the tap open while brushing.
• Do not throw any kind of waste into stagnant water.
• Rainwater can be collected in containers and used.

AIR
Air is a mixture of gases. It is present in the lower layer of the atmosphere. Moving air is called wind and it possesses a lot of energy.

Importance of Air
• All living things breathe in air for their survival.
• Green plants take in carbon dioxide present in the air to prepare their food.

• Animals take in oxygen for respiration.

• Wind is used to run mills for generating energy.

Air Pollution
The process by which the clean air gets contaminated with other gases, dust and chemicals is called air pollution.

How to Save Air from Being Polluted?
• Unnecessary burning should be decreased.
• Tall chimneys should be present in factories.
• More and more trees should be planted.
• Using pollution free vehicles.

FOSSIL FUELS

The remains of plants and animals which were buried deep under the earth got converted into fossil fuels. These fuels contain a lot of energy. Some of the fossil fuels are coal, charcoal, petrol, diesel etc.

Importance of Fossil Fuels
We use fossil fuels mainly to generate energy. This energy can be used for doing any sort of work. Different fuels are used for different purposes.

1. Coal : To run the steam engine.

2. Petrol : To run various vehicles.

3. Kerosene : To fill in lamps and stoves.

4. LPG : Used for cooking.

How To Save Fuel?
• Cooking on a slow flame saves fuel
• Vehicles should be kept in proper condition as old and damaged vehicles consume more fuel.
• Food cooked in covered vessels employs less fuel.
• Avoid heating the food again and again.

Assignment: Read Chapter 10 carefully and Do Pg No.106,109 in the text book.

           12 / OCTOBER / 2020           

 GENERAL SCIENCE 

CHAPTER-  2 The Respiratory System

Revision

Now watch this video to help you understand better.

BREATHING

The process during which air rich in oxygen is taken in and air rich in water vapour and carbon dioxide is given out is known as breathing.

INHALATION

The process of taking in of air is known as inhalation.

EXHALATION

The process of giving out of air is known as exhalation. Breathing is a continuous process and occurs throughout the life of all organisms.

RESPIRATION

The process of breaking down the complex food substances with the help of oxygen and releasing energy is known as respiration.

Why do we respire?

As all machines need energy to work. Similarly, our body also needs energy for its various activities. This energy is obtained by respiration of food we eat. Respiration takes place inside the body cells.

THE RESPIRATORY SYSTEM

The organs that help in respiration together form the respiratory system. Thus, the various parts of respiratory system includes the nose, nasal passage, windpipe and lungs.

Nose and Nasal passage

We breathe through the nose or nostrils. The nostrils contain hair. These hair trap dust particles and germs and send clean air for respiration. Thus, we should always

breathe through our nose.

Windpipe

The air from the nasal passage reaches the lungs through the windpipe and then divides into two bronchi and then enter into the two lungs.

LUNGS

Lungs are the main respiratory organs in our body. They are a pair of spongy, elastic and bag like structures. When we breathe in, the lungs gets filled with fresh air. This air is taken by the blood to all the parts of the body and the used air is then given back to the lungs.

The air we inhale contains a lot of oxygen which is taken by the lungs. In our body, the percentage of oxygen decrease because our body takes oxygen for respiration and gives out carbon dioxide. This gas is then given out of the body.

AIR POLLUTION

The mixing of harmful components in air is known as air pollution. Air pollution effects our respiratory system and cause a number of diseases. The germs present in the air enter into the respiratory tract and multiply causing various allergic diseases.

Sneezing : When we inhale, the germs are trapped by the hairs present inside the nose. Sometimes, these particles are not trapped and cause irritation. Thus, sneezing occurs to throw these particles out.

Coughing : If unwanted particles enter the respiratory tract, then coughing occurs to throw these particles out.

Asthma : The breathing difficulty that occurs due to an allergic disorder is known as asthma.

Other than these, polluted air causes common cold, headache, dizziness, inflammation of lungs and bronchitis. Common cold results from the germs that attack our body resulting in fever, nasal discharge, headache and reddening of eyes.

Precautions

1. Eating healthy food keeps our body healthy and prevents us from diseases.

2. Common cold is a communicable disease. Thus, keep a handkerchief infront of your nose while sneezing.

3. Take personal care of health and hygiene.

4. In case of severe cold, visit the doctor.

How to ensure healthy breathing ?

1. Morning walk is very helpful because the air is clean and fresh.

2. Alpha breathing process increases the capacity of the lungs.

3. People during yoga maintain good posture which helps to breathe properly.

4. Too much of fatty foods reduce the capacity of breathing and in turn leads to obesity.

Thus, healthy food and good posture helps in healthy breathing.

Assignment : Complete the following in your Science-OCB .

Do Exs D,E,F on page No. 87.

           08 / OCTOBER / 2020           

GENERAL SCIENCE

CHAPTER- 8  WATER

SOLUBILITY AND SOLUTION

Water is known as universal solvent because it can dissolve all kinds of solids, liquids or gases to little or more extent. According to the solubility, the substances may be classified as soluble or insoluble substances.

• The substances which dissolve rapidly in water are called soluble substances.

Examples : Common Salt and Sugar.

• The substances which dissolve very little or do not seem to dissolve are known as insoluble substances.

Examples : Mud and Sand.

SOLUTION
The mixture formed by dissolving a soluble substance in water is known as solution.

Common Terms used in the formation of a Solution
1. Solvent : A liquid which dissolves other substances in it is called solvent. For example, common salt dissolves in water and hence water is a solvent.

2. Solute : A substance which dissolves in liquid is called solute. Example : In the above example common salt is the solute.

3. Unsaturated Solution : A solution which has less amount of solute is known as unsaturated solution.

4. Saturated Solution : A solution which has large amount of solute is known as saturated solution.

Conditions which enhance the formation of a solution :
1. Solute and solvent must be capable of mixing.
2. High temperature enhances the formation of a solution.
3. Stirring helps in quick formation of the solution.
4. Solute should be in the form of a fine powder, as it helps in the formation of solution quickly.

IMPURITIES AND ITS REMOVAL
There are two types of impurities soluble and insoluble.

Both these impurities are present in water. Thus the removal of these impurities become important.

Some methods of removing insoluble impurities
1. Filtration- The separation of insoluble impurities with the help of filter paper or muslin cloth is known as filtration.
Filtrate : The clear liquid which passes through the filter paper is known as filtrate.
Residue : The solid impurity left on the filter paper is known as residue.

2. Sedimentation and Decantation
The process of settling down of heavy impurities is known as sedimentation and then removing the clear liquid from the top is known as decantation.

Step I: The impure water is allowed to stand for sometime.

Step II: The impurities settle down at the bottom of the container as sediments.

Step III: The clean water poured out into a separate container is known as decantation.

Removal of soluble impurities
Soluble impurities are very finely mixed in water. Hence, their removal becomes bit difficult. These impurities can be removed by evaporation or by distillation.

Assignment : Complete the following in your Science-OCB .

Do Ex- A, B, C on page No- 86, 87.

A. Tick the right choice:

1. Which of the following is pure form of water?

a) surface water b) rainwater

2. Which gas is used to disinfectant water?

a) chlorine b) bromine

3. When water from rivers is fed into big reservoirs. The process is 

a) pumping b) sending

4. The process of filtration with the help of muslin cloth is

a) straining b) removing

5. Water which forms a lather with soap easily is known as:

a) soft water b) hard water

B. Fill in the blanks with the given options below:

Saturated, Oxygen, Soluble, float, sediments

1. ______ impurities are very finely mixed in water.

2. The impurities settle down at the bottom of the container are ______.

3. Lighter substances _______ in water.

4. Excess of salt present in ______ solution.

5. ________ gas helps in the respiration.

           24 / SEPTEMBER / 2020           

GENERAL SCIENCE

CHAPTER-  8  WATER     
Water purification at a small level:
The water brought to the houses may sometimes carry germs in the way. These germs may be removed by:
Boiling and Straining: Water may be boiled and then filtered with the help of a clean cloth.
Storage: The purified water should be stored in clean containers with a lid.

Chlorine Tablets

Chlorine tablets are used to kill the germs at a small level. It is simply added to drinking water, then kept for sometime before consuming.

Hard and Soft Water
Soft Water: Water which forms lather with soap easily is known as soft water.
Example: Rainwater and distilled water.

Hard Water: Water which does not form lather soap is known as hard water.
Example: Well water and Spring water.
Water contain Dissolved gases
Dissolved gases in water provide taste to the water.

Oxygen dissolved in water helps in the respiration and survival of aquatic life.

Carbon dioxide dissolved in water helps in photosynthesis of aquatic plants.

Assignment : Read Chapter 8 and Do Pg No. 80 in the text book.

           21 / SEPTEMBER / 2020           

GENERAL SCIENCE

CHAPTER-  8  WATER     

Water plays a key role in carrying out important activities like drinking, cooking, bathing, irrigation etc. Hence, life is possible on the earth due to the presence of water. Nearly, three- fourths of the earth's surface is covered with water. It is present in all living things.

Occurrence Of Water

Water is present almost in all natural things like plants, animals, rocks and air. In the solid state, it exists as snow, in snow covered mountains. It is present in rocks and minerals as water of crystallisation and as water vapours in air.

Surface and Underground Water

Surface Water: Water which is present on the surface of the earth is called surface water. 

Example : Rain water, Sea water

Underground Water: The water which collects over the hard rock below the earth is called underground water.

Example: Well water, Spring water.

Now watch this video to help you understand better.

Water Cycle

Circulation of water from the earth's surface to the atmosphere and back to the earth is called water cycle.

Potable Water

Water which is clean and pure and is for human consumption is known as potable water.

Need for Potable Water

The water which is present in lakes, rivers, and as underground water, can only be used for human consumption. Thus, there exist an intense need for potable water. 

Characteristics of Drinking Water:

It should be Colourless, Odourless, Free from suspended impurities, Free from bacteria and germs, Free from harmful compounds.

Purification of Water

The impure water has to undergo series of steps for the process of purification.

Step 1 Pumping

Water from rivers, lakes is fed into pumping station where it is pumped into big reservoirs.

Step 2 Sedimentation

Water is collected in reservoirs. Heavy particles settle down in this tank. Chemicals like alum are added to speed the process of sedimentation.

Step 3 Filtration

After sedimentation, the water is filtered through a clean sandbed to remove the finer suspended particles.

Step 4 Chlorination

Water is then disinfected with a very small quantity of chlorine gas to kill bacteria.

Assignment : Read page No. 76 to 78 of Chapter 8
Do the following in your Science- OCB. Do Ex D, E, F on page No. 73 and 74.

F. Write True or False:

1. Matter doesn't occupy space.

2. Air is matter.

3. Light things rise up.

4. Food is also matter.

5. There are two states of matter. 

           14 / SEPTEMBER / 2020           

GENERAL SCIENCE

CHAPTER-  1 OUR BODY SYSTEMS  

(Revision) 

Just as a building is made up of bricks our body is made up of cells. Cells are the building blocks of our body. These cells join together to form complex organs and organ systems. Cells are the smallest functional unit of our body 

CELLS

TISSUES

Many cells join together to form a tissue. Many tissues join together to form an organ; for example a kidney.

Many organs join together to form an organ system; for example the excretory system.

Number of organ systems join together and function together to form an organism; for example a Human being.

Examples of- Cells -> Tissues -> Organ -> Organ system -> Organism

PLANTS AND ANIMALS

HUMAN BABY

 

HUMAN CHILD

Now watch this video to help you understand better.

ORGAN SYSTEMS
Now watch this video to help you understand better.

When few organs together carry out the major function for the body. They form an organ system.The different Organ systems help a body to function properly. There are eight important systems in the body.

IMPORTANT POINTS TO REMEMBER

THE SKELETAL SYSTEM: The skeletal system  comprises of a bony framework. It gives shape and support to our body. There are 206 bones in our body. When joined together, they form a united framework called skeleton.

THE MUSCULAR SYSTEM: Muscles are attached to the bones.  It helps in body movement. There are more than  500 muscles in our body

THE NERVOUS SYSTEM: The nervous system is the control center of the human body. It is made up of the brain, the spinal cord and the nerves.This system helps us to think, reason and act accordingly.

THE DIGESTIVE SYSTEM: The purpose of the digestive system is to turn the food you eat into something useful for the body so your cells can use it to make energy.

THE RESPIRATORY SYSTEM: The respiratory system supplies blood with oxygen through breathing, in order for the blood to deliver oxygen to all parts of the body.

THE CIRCULATORY SYSTEM: This system is concerned with circulating blood to deliver oxygen and nutrients to every part of the body.

THE EXCRETORY SYSTEM: The excretory system filters the blood to remove wastes that could be harmful to the body.
THE REPRODUCTIVE SYSTEM: The human reproductive system makes it possible for humans to have babies.

Now watch this video to help you understand better.

Assignment : Do the following in your Science- OCB

Do Exs - A, B and C on page No.72 and 73.

A.Tick the right option:

1. Which of the following is a solid?

a) bread  b) milk

2. What is filled in balloons?

a) hydrogen gas b) stones

3. Matter can be felt by our:

a) senses b) hands

4. Matter is made up of:

a) molecules b) bricks

5. How many states of matter are there? 

a) three  b) two

B. Fill in the blanks with the given options below:

matter, gaseous, perceived, increases, molecules.

1. Matter can be ______ by senses.

2. Air blown ______ the size of balloon.

3. Matter is made up of ____________.

4. There are three states of _________.

5. Steam is the ________ state of matter.

C. Give one word for the following:

1. State in which molecules are tightly packed.

S _________.

2. The smallest particle of matter.

A __________.

3. It takes the shape of a container.

L ________.

4. Gas filled in weather balloons.

H ____________.

5. Atoms combine to form

M ___________.

              10 / SEPTEMBER / 2020              

GENERAL SCIENCE

CHAPTER-  7 STATES OF MATTER

Can states of matter be changed?

Now watch this video to help you understand better:

When some solids are heated, they can change into liquid or gas.

Some gases when cooled, change into liquids and solids.

Assignment: Read Chapter 7.

              07 / SEPTEMBER / 2020              

GENERAL SCIENCE

CHAPTER-  7 STATES OF MATTER                                                    

What ever is present around us is known as matter. The table, chair, black board, chalk, duster, bags, air, water etc. can be called matter.
In other words we can see and feel matter by our senses.
Matter is anything which occupies space, has weight and can be perceived by our senses.
A school bag containing books is matter.

Now watch this video to help you understand better.:

Composition of Matter
Matter is just like a closed sac of grain.

When it is opened, it gives you wheat grains which are like molecules.

When it is ground, it gives you small flour particles which are like atoms.

Solid State
If molecules are present closer to each other, then it is in a solid state. Solids have a definite shape.

Liquid State
If molecules are present away from each other, then it is in a liquid state. Liquids take the shape of the container.

Gaseous State
If molecules are present very far away from each other, then it is in a gaseous state.
Gases do not have any definite shape.

Assignment: Read page No.67 and 69 of Chapter 7.