Current Affairs 4th Class

Addition LEARNING OBJECTIVES This lesson will help you to:—

• be able to find the sum of two numbers.
• be able to solve real life problems based on addition.
• explore various facts of addition.
• be able to define addition.
• be able to define the terminology of addition.
• be able to explain the properties of addition.

  Real Life Example Addition is used in every sphere of our life. It is used in our daily activities like purchasing grocery, all monetary transactions like in banks etc.   QUICK CONCEPT REVIEW WHAT IS ADDITION? Combining two or more objects of same kind is known as addition. It is bringing two or more numbers (or things) together to make a new total. Addition is finding the total, or sum, by combining two or more numbers. Some other names used in addition are Sum, Plus, Increase & Total.   TERMINOLOGY Sum The result obtained after addition is called sum. It the result obtained after adding one number to another.   Addend The numbers that are to be added are called addends. ADDEND + ADDEND = SUM For example:        50 + 20 = 70 Here,                        50 = Addend                                    20 = Addend                                    70 = Sum PROPERTIES OF ADDITION

When we add 1 to any number, the answer is always its successor

For Example: Tina had 1 fish in her fish tank.              Her mom gave her another fish on her birthday. How many fish are there in all? There was 1 fish in the fish tank. One more is added to it. Therefore, total number of fish in the fish tank = 1 + 1 = 2

When we add zero to a number, the answer is the number itself.

That is, 29 + 0 = 29 Hence, we can say that when we add zero to a number, the answer is the number itself.

If we change the order of numbers while adding, the sum does not change.

For example: 25 + 34 s 59 Here, Addend 1= 25 Addend 2 =3 4 Sum =59 If we interchange the addends with each other, that is 34 becomes addend 1 & 25 becomes addend 2. The sum remains the same. That is, 34 + 25 = 59 Hence, we can say that if the order of the numbers to be added is changed, the sum will remain the same. DIFFERENT WAYS TO MAKE A NUMBER Let us find out different ways to form the number 50. AII the petals of the flower represent ways to form the number 50. We can add many more petals to this flower.     Amazing Facts  The sum is always greater than the numbers being added except when one of the numbers being added is zero. If you add up the numbers 1 to 100. Consecutively (1 + 2 + 3 + 4 + 5….) the total is 5050. more...

LEARNING OBJECTIVES This lesson will help you to:—

• be able to find the difference between two numbers.
• be able to solve real life problems based on subtraction.
• explore various facts of subtraction.
• be able to define subtraction.
• be able to define the terminology of subtraction.
• be able to explain the properties of subtraction.

  Real Life Example Subtraction is used in every sphere of our life. It is used in our daily activities like purchasing grocery, all monetary transactions like banks etc. More on top????? No need to stop. More on the floor????? Go next door, get ten more. Numbers the same????? Zero’s the game.   QUICK CONCEPT REVIEW   WHAT IS SUBTRACTION? Subtraction is taking away some objects from a given collection. It is taking one number away from another. Some other names used in subtraction are Minus, Less, Difference, Decrease, Take Away, Deduct.   TERMINOLOGY Difference The result obtained after subtraction is called difference. It the result obtained after subtracting one number from another. Minuend The number that is to be subtracted from is called minuend. Subtrahend The number that is to be subtracted is called subtrahend. MINUEND – SUBTRAHEND = DIFFERENCE   For example, 50 - 20 = 30 Here,           Minuend = 50                 Subtrahend = 20                   Difference = 30   PROPERTY OF SUBTRACTION

When we subtract a number from itself, the answer is always Zero.

For example: 6884 – 6884 = 0

When we subtract zero from a number, the answer is the number itself.

For example: Monty saw 9 mangoes on a mango tree. He wants to eat the mangoes but could not reach them. How many mangoes were left on the tree?   There were 9 mangoes on the tree. Monty could not get any mango. It means still there were 9 mangoes on the tree. This can be written as 9 – 0 = 9 Therefore, there were 9 mangoes left on the tree. Hence, we can say that when we subtract zero from a number, the answer is the number itself.     SUBTRACTION WITH NUMBER LINE 72 – 45 =? 5 + 20 + 2 = 27 Therefore, 72 - 45 = 27 USES OF SUBTRACTION

To find out how many are left: In a singing competition, 25 students out 75 qualified for the next round? How many students were left unselected?

Here we have to find the number of students who were left unselected. Whenever we have to find how many are left we use subtraction.   Amazing Fact The above question can solved with an amazing shortcut also. 5000 – 1832 =? 5000\[\to \]5000-1\[\to \]4999 -1832\[\to \]1832-1\[\to \]1831 ________________________________                                       3168   Therefore, number of students left unselected = Total number of students - Number of students selected = 75 - 25 = 50 more...

LEARNING OBJECTIVES This lesson will help you to:-

• be able to find the product of two numbers.
• explore various facts of multiplication.
• be able to define the terminology of multiplication.
• be able to explain the properties of multiplication.

  Real Life Examples Multiplication is used in daily household activities. For example, if 2 glasses of water is required to cook 1 glass of rice. Then how many glasses of water are required to cook 5 glasses of rice. 72 people can sit in one train compartment. How many people are there on a train with 15 such compartments? QUICK CONCEPT REVIEW MULTIPLICATION A hen laid 28 eggs & the chicks were born. She wants to distribute sweets to her friends & relatives. They have 20 families of friends & relatives.   She wants to give 6 sweets to each family. She started counting the number of sweets to be purchased from the market. She finds it quite difficult and time consuming to count the total number of sweets to be purchased. Can you help her find out an easier way to do so? 6 sweets are to be distributed to each family and there are 20 families in all. So instead of adding 6 again and again 20 times, we can simply multiply 6 by 20. The answer will be the same in both the cases. 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 = \[6\times 20=120\] sweets. Therefore, we can say that multiplication is a short form of repeated addition. It is a mathematical operation that indicates how many times a number is added to itself. Multiplication is the process of finding the product of any two numbers.   TERMINOLOGY When multiplication is considered as repeated addition: The, number to be multiplied is called the multiplicand. The number of multiples is called the multiplier. When any two numbers are multiplied: The numbers to be multiplied are called factors or multiplicands. The result after multiplication is known as the product. PROPERTIES OF MULTIPLICATION    Amazing Facts Multiplying two same numbers with 5 at ones place. Example, \[45\times 45=?\] The last two digits of the answers will always be 25. Now multiply 4 by the number that follows it i.e. \[5.\left( 4\times 5=20 \right)\] Write the number in front of 25.  \[\underline{2025}\] Therefore, \[45\times 45=2025\] Multiplying by 11. For multiplying any number by 11, just place the first and last digit as it is on their respective places and add the two digits and place the sum between the first and last digit. Example,                                      Th       H           T           more...

LEARNING OBJECTIVES This lesson -will help you to:

• learn and study about the renewable and non-renewable sources of energy.
• understand the advantages of reusing and recycling.
• learn about the concept of conservation of energy.
• study about global warming and factors behind it.

  Real Life Examples

• Nowadays we can see that people are installing solar panels on their terrace that convert the solar energy into the electrical energy.
• Solar cells and solar batteries are also used a lot nowadays.
• Since past many years, stress is being given on planting more and more trees. This activity is also promoted in schools. Growing trees is a step towards the green revolution wherein we are working towards minimizing the effects of global warming and greenhouse effect.

  QUICK CONCEPT REVIEW Energy: Energy means the ability to cause change. This change could be in moving a certain object or some change in the environment. Energy is the vital form powering our society, industry and eventually our day to day life. There are various sources of energy but broadly energy sources can be classified as renewable and non-renewable sources.   RENEWABLE SOURCES

• Those sources of energy that can be replenished after short period of time are called renewable sources.

Example: Solar energy, hydro (water) power, wind, biomass etc.

• There are many advantages associated with renewable energy.
• Solar energy is free and renewable and as long as the sun shines, you have a source of energy.
• Like solar energy, wind energy offers you a clean, alternative and renewable source of energy. Electricity can be generated using the wind energy.
• Hydroelectricity harnesses the power of downstream water flow to generate electricity.
• Geothermal energy is generated from the heat extracted from the earth and is transferred for use in your home. Geothermol is sustainable and renewable and offers a very cost-effective way to heat your home.                              

Many forms of renewable energy produce no solid waste, reducing pollution production.              The goal in using renewable energy sources is to reduce the negative environmental effects associated with non-1 renewable energy sources such as coal and natural gas. Opting to use a renewable energy source is cost- effective? And also helps protect the environment from the risks of fossil fuel emissions of non-renewable energy sources.   Historical Preview In the beginning, the sun was the only source of energy. People would gather food during the day, and when the sun went down at night, they would search for shelter from the cold. Eventually someone discovered fire more...

LEARNING OBJECTIVES This lesson will help you to:

• understand various internal body parts.
• know about the function of teeth.
• learn about food and digestion.
• study the importance of sanitation and diseases.

  QUICK CONCEPT REVIEW Some of the important body systems which include the vital organs are: 1. Circulatory system: All parts of our body need oxygen and nutrients. This work is done by our blood. The blood is circulated throughout the body. The organ which circulates the blood is our Heart. It pumps the blood. The blood flows through blood vessels. Heart and blood vessels together form circulatory system. Blood vessels are of three types: artery, vein and capillary. Our heart is protected from injuries by our ribs. The ribs form a cage like structure to protect the heart from any external damage. There are 12 pairs of ribs in human beings.   2. Respiratory system: We take oxygen inside and give out. The respiratory system regulates the exchange of gases. It is mainly about taking oxygen inside and the waste gases such asout of the body. It includes:

• Nose: We take air inside through the nose. There are small hairs in the nose which prevent the entry of dust particles.
• Pharynx: From nasal cavity air goes to pharynx from where it goes to trachea. Tracheas are attached to lungs.
• Lungs: These are the major respiratory organs where the exchange of gases takes place.

  3. Nervous system: It coordinates all the actions of our body. It mainly consists of brain. Brain: It is the part of our body which controls all the actions of body. Example: walking, talking, swallowing, taste and smell etc all are regulated by our brain. In short we can say anything we do, our brain is involved in it. 4. Teeth and its functions: We have two sets of teeth during our lifetime; they are milk teeth/deciduous. Teeth and permanent teeth. There are altogether 20 deciduous teeth and 32 permanent teeth.   Enamel Transparent or milky white colour. The hardest tissue in a human body (harder than bone)   Dentine                                     Slightly yellowish in colour   Pulp Filled with blood vessels and nerve fibres. We have different types of deciduous teeth: incisors canines, first molars, and second molars. Incisor - to cut food like a pair of scissors. Canine - to tear food like a fork. First molars - can grind food. Second molar – larger than first molars, can grind food like first molars do.   FUNCTIONS OF TEETH Food needs more...

LEARINING OBJECTIVES This lesson will help you to:

• learn about the solar system.
• study about different planets and their moons.
• learn about stars.
• learn about asteroids.
• learn about the movement of planets in the

  Real Life Example

• In the night if we see the sky closely, we can see several shooting stars. These shooting stars are actually meteors that are burning

  QUICK CONCEPT REVIEW UNIVERSE Solar System: The sun, its planets and all the objects moving around them collectively are called solar system. The solar system is in a galaxy known as "the milky way". About 99.86 percent of the mass of the solar system is made up of the sun. There are 8 planets in the solar system.     SUN

• Sun is a ball of hot, burning gases. It is made of gases called hydrogen and helium.
• Sun is the nearest star to the earth.
• Sun is the source of all energy for life on earth.
• The outside of the sun is 11,000 degrees Fahrenheit.
• On the sun's surface, there are dark patches known? as sunspots. These are patches of gas that looks, dark since they are cooler than their surroundings.

  PLANETS

• Planets are heavenly bodies, which revolve around the sun in elliptical orbits.
• All planets fall in 2 groups Inner Planets: Mercury,: Venus, Mars and Earth are called inner planets. Outer Planets: These are Jupiter, Saturn, Uranus and Neptune,                                
• Between Inner &. Outer planets, there is a ring of small bodies, which are made of rock & metal, these are called Asteroids. They also keep moving around the sun. This ring is also called Asteroids belt.
• The inner planets are also called the rocky planets, because they are made of rocks.

  Amazing Facts

• A person of 60 kg weight barely will weigh 10 kg on moon. That means, you would weigh 1/6th of your weight on moon. This happens due to gravitational pull at different places.
• It takes about 1.25 seconds for moonlight to reach the earth whereas sunlight reaches earth in 8 minutes 19 seconds, so you can judge how close moon is to us & how far sun is from earth.
• In space, astronauts cannot cry, because there is no gravity, so the tears can’t flow.
• Saturn has such a low density that it would float if put in water.

  MERCURY

• Mercury has large variations in temperatures during day and night.
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 LEARNING OBJECTIVES This lesson will help you to:

• study about the use of animals for transport.
• study various modes of transportation.
• learn and familiarize with different currency notes and coins used across the world.
• study and learn different land forms, languages, clothing, food habits, and some idea of another country.

  Real Life Examples

• Whenever we have to go in a train, we have to buy tickets well in have to buy tickets well in advance and have to board the train from the station mentioned in the ticket.
• We can see lot of people and things in the railway station like-coolies, people selling different items, food stalls, book stalls, washer men etc.

  Historical preview

• In the past, pigeons were used as messengers for sending the letters.
• In the past, currency was not a medium of exchange. In those days, barter system was prevalent wherein goods were exchanged for goods. This system is no longer prevalent.

  QUICK CONCEPT REVIEW

• Man has found ways to move around and communicate with each other on the earth as well as space. Going from one place to another was not easy for early man. He used animals to pull carts and sledges or used boats and rafts to cross rivers. All these took a very long time.
• The three types of transport are- land, air and water.

  USE OF ANIMALS FOR TRANSPORT Different animals are used in different areas depending upon the terrain, utility and convenience to the human beings. They are used to carry both goods and people. Forests: In forests, elephants are used to carry logs, heavy trees and people. Deserts; Camel is generally used in deserts. Their main use is to carry people around in the dusty deserts. Camels have the advantage as they can stay without water for days, which is scarce in deserts. Towns: Tongas are usually found in small towns. These are usually pulled by horses. Villages: Bullock Carts are used in villages to carry goods and people. These are also used to plough the fields which cannot be done manually. These carts are pulled by cattle. Hills: In the hilly areas, roads are usually narrow and sloping in nature. For carrying goods and tourists people ponies and mules are helpful.   LAND TRANSPORT This is the most common mode of transportation people use in their daily life. We can see various kinds of vehicles on road like cars, buses, rickshaws, cycle, trucks, scooters etc. For moving within the state people prefer road transportation. We can move from one state to more...

LEARINING OBJECTIVES This lesson will help you to:—

• study about how houses have changed over time.
• study about differences in rural and urban houses.
• study about waste accumulated in houses.
• learn about urban and rural waste.
• study about methods of reusing and reducing waste.
• study about diversity in animal habitat and shelters.
• study and learn about the nesting habits of different birds.
• learn about the concept of giving direction with respect to any landmark.

  Real Life Examples

• In slum areas we still see people living in miserable conditions and in houses that are made up of mud, hay stack and tin roofs.
• On highways we usually see large sign boards with arrows and directions and distance written on them to guide the travelers on their way.

  QUICK CONCEPT REVIEW House: Then and Now

• There is a great transition in the houses in which our grandparents lived and in which we live today.
• Earlier the houses were built in bricks with slate roofs, very few were wired for electric lights and there were no wall sockets.
• The homes then were not furnished as they are now.
• Earlier houses were done in lath and plaster from inside while today mostly drywall is used.
• In rural areas, there were "kuchha" houses that were made up of mud or hay stack or tin roof which can't withstand harsh weather. Slums in India have "kuchha" houses.
• Urban areas usually have 'pucca' houses that are made up of red brick walls and roof. Sometimes roof is made up of concrete also.              
• Urban areas have houses that are multi-storied.

  GARBAGE

• The waste from our houses is called domestic waste and it includes food wrappers, product packaging, paper, food waste and other materials that people want to get rid of.
• The wastes from urban and rural areas differ.
• We must all try to reduce and reuse waste.
• The improper handling and management of domestic waste from households are causing adverse effect on the public at large and this deteriorates the environment.                         
• Recycling is part of the waste disposal hierarchy- 8 Reduce. Reuse, Recycle.

  Some ways to reduce waste are:

• Recycle whenever possible to reduce the amount of garbage you end up putting in your bin.
• Sell give away or donate items that you don't want.
• Instead of throwing them away, compost your garden with food waste. Examples of items more...

LEARINING OBJECTIVES This lesson will help you to:

• learn about different games played at home and school.
• Understand the importance of play.
• Study about different occupations in local region country.
• study the relation between gender and work.
• study about different ways of recreation.

  Amazing Facts There are currently 17 countries with women’s as heads of government, heads of state, or both this, according to the UN, is more than double what it was in 2005. Mary Queen of Scots has been attributed to creating the world’s first golf course.   Real Life Example We of then see that in hospitals there are more females as nurses, which shows that nursing is a female dominated job.   QUICK CONGER REVIEW

• Games are played at different levels and by different persons of all age groups.
• Some games are played indoor while some are played only outside. Games played indoor are called as the indoor games whereas the games that are played
• outdoors are called outdoor games.
• Examples of indoor games are- table tennis, chess, board games, cards etc.
• Examples of outdoor games are- cricket, football, basketball, lawn tennis etc.
• Games played at home are usually indoor games whereas at school both indoor and outdoor games are played but more importance is given to outdoor games to encourage physical activities.
• Children need opportunities both to play with other children and to play on their own.
• When a game is played, there are fights, bonding and differences among the players. These fights or arguments may be due to confusion over some game moves or the rules of the games.
• Sometimes several restrictions are also imposed on certain games.
• We should always play the game fairly.

             Historical preview

• Women were not allowed to work outside their in homes earlier. Even today in many countries, women are kept in Burkhas and are not allowed to move out of their homes for work.

  IMPORTANCE OF PLAY

Play enables children to find out about themselves and the world. It allows them to:

discover, create, concentrate.                                       express ideas, develop speech, develop muscles,                              learn new skills,                                 learn how other people behave,                  share possessions,                                use the imagination,                              co-operate with others,                          act protectively towards someone less powerful than themselves,                                    

Play gives happiness.                              

Play helps prevent boredom.

Play can help reduce stress.

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LEARNING OBJECTIVES This lesson will help you to:—

• learn about matter.
• study different states of matter.
• know how one state changes into another state.

  Real Life Examples When a container containing ice cubes is placed in sunlight it can be observed that first it melts down to form liquid water. And then if it is left undisturbed in sunlight till evening. Some of the water gets evaporated. In the atmosphere and the quantity of water in the container gets reduced. Due to the increasing temperature of the earth, glaciers are melting, leading to the increase in the water level of the earth.   QUICK CONCEPT REVIEW What is Matter?

• Matter is something that has mass and occupies space.
• Matter is made of particles.
• The particles of matter are very small.
• The particles of matter are moving continuously.
• Particles of matter have space between them.
• Particles of matter attract each other because of force of attraction.

  STATES OF MATTER There are three states of matter;

• Solid
• Liquid
• Gases

  SOLID

• Has a definite shape.
• Has a definite volume.
• Molecules in a solid are very tightly packed.
• We cannot compress it.
• Solids are heavy.
• Solid does not flow.

       Example: Diamond. LIQUID

• Has no definite shape as it takes the shape of its container.
• It has definite volume.
• Molecules are loosely packed.
• It can be compressed.
• Liquid is lighter than solid..
• Liquid flows and hence is called fluid.

Example: Water. GASES

• Have neither definite shape nor volume.
• They are easily compressible.
• Molecules are far apart.

Example: Steam.   Amazing Facts Glass is actually a liquid; it just flows very, very slowly. Liquid oxygen is blue. Hot water freezes quicker than cold water   CHANGE OF STATE Matters can be changed from one state to another state. A solid can be changed into liquid and a liquid can be changed into gas. Most of the metals, which ore solid, turn into liquid on heating and turn into vapour on further heating. more...