Chapter 1: Food - Where does it Come from?
❖ Ingredients: The materials that are required to prepare a food item are known as the ingredients of that food item.
❖ Sources of food materials
❖ Edible Parts: The parts of plants that are consumed by animals and humans.
Edible parts of plants are fruits, leaves, stem, roots, etc.
❖ Based on their eating habits, animals can be classified into
❖ Nutrients: The components required by our body are known as nutrients.
❖ Major nutrients present in our food are carbohydrates, proteins, fats, vitamins and minerals in addition to water and dietary fibers.
❖ Test for Nutrients
❖ Obesity is caused due to intake of excess of fats and starchy food items.
❖ Marasmus and Kwashiorkor are protein energy malnutrition diseases.
❖ Balanced Diet: All the nutrients required by our body in the right quantities constitute a balanced diet.Chapter 3: Fibre to Fabric
❖ Fabrics are made of yarns and yarns are further made of fibres. Fibres can
❖ Cotton:
❖ Jute:
❖ Fibres to yarn:
❖ Yarn to fabric:
❖ Objects around us can be made up of one or more materials.
❖ Some of the criteria for sorting objects
❖ Different methods of separation of mixtures:
❖ Solution: It can be prepared by dissolving a substance in liquid.
❖ Saturated solution: It cannot dissolve any more of the substance in it.Chapter 6: Changes around Us
❖ Changes around us can be grouped as reversible change and irreversible change.
❖ Reversible changes: The changes after which original form can be achieved back
❖ Irreversible Changes: The changes after which original form can not be achieved back
❖ A change can occur by heating a substance. For example,
❖ Plant types: Plants are usually grouped into
Parts of a plant
❖ Stem
❖ Leaf
❖ Root
❖ Flower
❖ Skeletal system
❖ Movement
❖ Joints
❖ Movement in other animals
❖ Habitat: It is the type of environment where an organism lives.
❖ Adaptations: Specific features that enable a plant or an animal To live in its habitat are known as adaptations.
❖ Biotic components: Living things such as plants and animals in a habitat
❖ Abiotic components: Non-living things such as rocks, soil, air, and water in a habitat
❖ Types of habitat:
• Adaptations of Cactus:
• Adaptations of animals:
• Adaptations of Plants:
• Grasslands
❖ Aquatic habitat
❖ Ponds and lakes
• Adaptations:
❖ Living organisms: An organism is called living if it shows all the seven characteristics – nutrition, respiration, movement, sensitivity, reproduction, excretion and growth.Chapter 10: Motion and Measurement of Distances
❖ Non standard methods of measurement : Hand-span, foot-span, finger width, palm length, the distance of a step,
❖ two parts of the measurement of a quantity are number and unit.
❖ Nowadays, the International system of units (SI) is used as standard units all over the world.
❖ Metre (m) is the SI unit of length.
❖
❖ The length of a curved line can be measured with the help of a thread. Measurement of the thread on a metre scale gives the length of the curved line.
❖ Types of motion:
❖ Motion of an object is the change in its position with time.
❖ The fastness or slowness of the movement of an object is determined by measuring the distance travelled with time.Chapter 11: Light, Shadows and Reflection
❖ Types of objects
❖ Classification of objects by sense of vision
❖ A shadow is always grey or dark. It is obtained only on a screen.
❖ A pinhole camera is a simple optical device that forms an image without using a lens or a mirror.
❖ A mirror forms images by the reflection of light. The images formed by mirrors are virtual, erect, and of same size as object.
❖ Left-Right Inversion: The left of an image formed by a plane mirror appears as right and its right appears as left.Chapter 12: Electricity and Circuits
❖ Electric cell: It is a source of electricity. There are two terminals of a cell – Positive (+) and Negative (–).
❖ Electricity is generated in a cell because of chemical reactions that take place inside it.
❖ Electric Bulb: A bulb has a filament and two terminals.
❖ The filament gives off light when an electric current flows through it.
❖ The electric circuit provides a complete path for electricity To pass between two terminals of the electric cell.
❖ In an electric circuit, the direction of current is taken from the positive To the negative terminal of a cell that is connected To the circuit.
❖ A fused bulb does not emit light as No current flows through its filament.
❖ Electric switch: A switch either breaks or connects the circuit.
❖ A torch consists of a cell or a battery, a bulb, and a switch.
❖ Conductors allow the current To flow through it while insulators do not allow the current To flow through it.
❖ Examples of conductors are aluminium, copper, iron, and steel and insulators are plastic, wood, glass, and rubber.
❖ Conductors are used To make electrical wires and insulators are used To cover them.Chapter 13: Fun with Magnets
❖ Magnetite has the property To attract objects made of iron.
❖ The substance that can attract iron, cobalt, or nickel is known as a magnet.
❖ Magnet was discovered by a shepherd named Magnes around 2000 B.C. who lived in Magnesia, Greece.
❖ Materials that get attracted towards the magnets are the magnetic materials.
❖ Materials that do not get attracted towards the magnets are the non-magnetic materials.
❖ There are two poles of a magnet – North Pole (N) and South Pole (S).
❖ A freely suspended bar magnet always aligns along North-South direction.
❖ The direction at a place can be identified with the help of a bar magnet or a magnetic compass.
❖ A magnetic compass consists of a magnetic needle that always comes To rest in the North-South direction.
❖ In older days, sailors found direction by suspending bar magnets.
❖ Like poles always repel each other. Unlike poles always attract each other.
❖ An iron bar becomes a bar magnet when one of the poles of a bar magnet is rubbed on it several times. This is known as touch-stroke method.
❖ A magnet looses its magnetic property when dropped from a height, hammered, or heated.
❖ Magnets can be stored safely as follows.
❖ Magnets should be kept away from cassettes, CDs, mobile, TVs, plastic cards, etc.Chapter 14: Water
❖ Water is essential for life.
❖ Wells, rivers, or lakes are sources of fresh water.
❖ Ocean and sea water is not potable because they dissolve large amount of salt in them.
❖ Water Cycle: The circulation of water between rivers, lands and clouds is known as water cycle.
❖ Clouds are formed during the process of condensation.
❖ Heavy rain in a short period of time causes flood.
❖ No rain for a long period causes drought.
❖ Most of the potable water (drinking water) becomes available To us as ground water.
❖ There is an immediate requirement To harvest water. The basic idea behind rainwater harvesting is ‘Catch water where it falls’.
❖ In rainwater harvesting method, the stored rainwater is used To recharge ground water.
❖ In rooftop rainwater harvesting system, the rainwater is collected from rooftop in a storage tank. It allows the water To go inTo the pit through pipes. This water seeps and refills the ground water.Chapter 16: Garbage In, Garbage Out
❖ The garbage collected in the garbage trucks is disposed in low lying open areas known as landfill.
❖ To deal with garbage, useful and non-useful components are separated.
❖ The useful components (that rot completely) include fruit or vegetable peels, paper bags, dried leaves, etc. They must be dumped in the green bins.
❖ The non-useful components (that do not rot) include aluminium wrappers, glass pieces, old shoes, plastic bags, etc. They must be dumped in the blue bins.
❖ Composting
❖ Recycle of materials
❖ Dealing with garbage
❖ Moving air is called wind.
❖ Air occupies empty spaces.
❖ Air is a mixture of many gases.
❖ Composition of air
❖ During photosynthesis, oxygen is released. Hence, it gets replenished in the atmosphere.
❖ Animals take oxygen and produce carbon dioxide during the process of respiration.
❖ Aquatic animals use air dissolved in water for respiration.
❖ Dust and smoke can be seen as a streak of light when sunlight enters a dark room through a slit.
❖ Windmill generates electricity when wind turns its fan rapidly.
❖ Windmills are also used To draw water from wells and To run flour mills.
❖ Air helps in the flight of birds and insects and in the movement of sailing yachts, gliders, airplane, paper airplane, etc.
❖ Ingredients: The materials that are required to prepare a food item are known as the ingredients of that food item.
❖ Sources of food materials
• Plant sources: Plant parts
• Animal sources: Milk, meat, eggs, etc
• Animal sources: Milk, meat, eggs, etc
❖ Edible Parts: The parts of plants that are consumed by animals and humans.
Edible parts of plants are fruits, leaves, stem, roots, etc.
❖ Based on their eating habits, animals can be classified into
• Herbivores - Eats only plants. Example: Cow, Deer, etc
• Carnivores - Eats only other animals. Example: Dog, Lion, etc
• Omnivores - Eats both plans and animals. Example: Crow, Birds, etc
Chapter 2: Components of Food• Carnivores - Eats only other animals. Example: Dog, Lion, etc
• Omnivores - Eats both plans and animals. Example: Crow, Birds, etc
❖ Nutrients: The components required by our body are known as nutrients.
❖ Major nutrients present in our food are carbohydrates, proteins, fats, vitamins and minerals in addition to water and dietary fibers.
❖ Test for Nutrients
Nutrient | Carbohydrates | Proteins | Fats |
Reagent used | Iodine solution | Alkaline copper sulphate solution | Crushing a food item |
Result | Appearance of blue-black colour | Appearance of violet colour | Appearance of oily translucent patch |
Nutrients | Sources | Deficiency diseases |
Carbohydrates: Energy giving foods | Wheat, potato, maize, sweet potato, etc. | Lethargic body |
Fats : Energy giving food | Oil, ghee, milk, butter, etc. | |
Proteins: body building foods. | Pulses, milk, fish, meat, etc. | Weaker muscles |
Vitamins and minerals: Protective food Vitamin A Vitamin B Vitamin C Vitamin D Minerals Iodine Iron Calcium Phosphorous |
Carrot, papaya, fish oil, etc Liver, wheat, rice, etc. Lemon, amla, tomato, etc. Milk, butter, eggs, fish, etc Spinach, ginger, fish, etc. Spinach, apple, liver, etc. Eggs, milk, etc Milk, banana, wheat, etc. |
Night blindness Beriberi Scurvy (bleeding gums) Rickets Goitre Anaemia Weak bones and teeth Weak and spongy bones |
Dietary fibres: Prevents constipation | Dahlia, potatoes, fresh fruits, and fibrous vegetables, etc | Constipation |
Water: Hydrates and cools the body | Direct drinking and in fruits and vegetables | Dehydration and skin dryness |
❖ Obesity is caused due to intake of excess of fats and starchy food items.
❖ Marasmus and Kwashiorkor are protein energy malnutrition diseases.
❖ Balanced Diet: All the nutrients required by our body in the right quantities constitute a balanced diet.Chapter 3: Fibre to Fabric
❖ Fabrics are made of yarns and yarns are further made of fibres. Fibres can
• Natural fibres: Obtained from plants and animals. Example : Cotton and Jute
• Synthetic fibres: Not obtained from plant or animal resources. Example: Nylon
❖ Cotton:
• Source: Cotton balls which are fruits of cotton plant
• Fibres are separated from the seeds by ginning.
• Fibres are separated from the seeds by ginning.
❖ Jute:
• Source: The stems of the jute plants.
• Jute fibres are then separated by hand.
• Jute fibres are then separated by hand.
❖ Fibres to yarn:
• The process of making yarn of fibres is called spinning.
❖ Yarn to fabric:
• Weaving: Process of arranging sets of yarns together to make a fabric. It is done on looms.
• Knitting: A single yarn is used to make a piece of fabric. It is done by hand and also by machines.
Chapter 4: Sorting Materials Into Groups• Knitting: A single yarn is used to make a piece of fabric. It is done by hand and also by machines.
❖ Objects around us can be made up of one or more materials.
Material | Objects made of these materials |
Paper | Books, newspaper, calendars, toys, etc. |
Wood | Chair, table, plough, pencil, etc. |
Plastic | Pen, plate, toys, bottle, buckets, etc. |
Leather | Bags, shoes, etc. |
❖ Some of the criteria for sorting objects
• lustrous and non lustrous.
• hard and soft.
• soluble in water and insoluble in water.
• float or sink in water
• Transparent, translucent or opaque
• Transparent substances - Substances or materials through which things. Example: Glass
• Translucent substances - Substances or materials through which things can be seen but not clearly. Example: butter paper
• Opaque substances - Substances or materials through which things cannot be seen. Example: wood, metals
Chapter 5: Separation of Substances• hard and soft.
• soluble in water and insoluble in water.
• float or sink in water
• Transparent, translucent or opaque
• Transparent substances - Substances or materials through which things. Example: Glass
• Translucent substances - Substances or materials through which things can be seen but not clearly. Example: butter paper
• Opaque substances - Substances or materials through which things cannot be seen. Example: wood, metals
❖ Different methods of separation of mixtures:
• Hand picking: It is used to separate larger size impurities such as stone and husk from grains.
• Threshing: It is used to separate grains from stalks by beating stalks.
• Winnowing: It is used to separate heavier and lighter components of a mixture by wind or by blowing air.
• Sieving:
• Threshing: It is used to separate grains from stalks by beating stalks.
• Winnowing: It is used to separate heavier and lighter components of a mixture by wind or by blowing air.
• Sieving:
⚬ It is used when the components of a mixture have different sizes.
⚬ It is used for separating pebbles and stone from sand; husk and stone from wheat.
⚬ The fine sand particles pass through the holes leaving behind bigger impurities on the sieve.
⚬ It is used for separating pebbles and stone from sand; husk and stone from wheat.
⚬ The fine sand particles pass through the holes leaving behind bigger impurities on the sieve.
• Sedimentation: In the mixture of sand and water, the heavier sand particles settle at the bottom by the process of sedimentation.
• Decantation: It is the process of removing water carefully from the mixture of sand and water after sedimentation
• Filtration: It is used to separate the components of a mixture of an insoluble solid and a liquid.
• Evaporation: It is the process of conversion of liquid into its vapour. It can be used to separate a solid dissolved in water.
• Condensation: It is the process of conversion of water vapour into its liquid form.
• Decantation: It is the process of removing water carefully from the mixture of sand and water after sedimentation
• Filtration: It is used to separate the components of a mixture of an insoluble solid and a liquid.
• Evaporation: It is the process of conversion of liquid into its vapour. It can be used to separate a solid dissolved in water.
• Condensation: It is the process of conversion of water vapour into its liquid form.
❖ Solution: It can be prepared by dissolving a substance in liquid.
❖ Saturated solution: It cannot dissolve any more of the substance in it.Chapter 6: Changes around Us
❖ Changes around us can be grouped as reversible change and irreversible change.
❖ Reversible changes: The changes after which original form can be achieved back
• Folding of a paper
• Rolling out a roti from a ball of dough
• Stretching of rubber To its normal size
• The melting of ice candy
• Dissolving sugar in water
• Heating (or melting) of wax, etc.
• Stretching of rubber To its normal size
• The melting of ice candy
• Dissolving sugar in water
• Heating (or melting) of wax, etc.
❖ Irreversible Changes: The changes after which original form can not be achieved back
• Ripening of fruits
• Souring of milk
• Cooking of food
• Sawing of a piece of wood
• Cutting of paper
• Burning of paper
• Cow dung To biogas,
• burning of candle etc.
• Souring of milk
• Cooking of food
• Sawing of a piece of wood
• Cutting of paper
• Burning of paper
• Cow dung To biogas,
• burning of candle etc.
❖ A change can occur by heating a substance. For example,
• The iron blade, when heated, becomes slightly larger in size (expands) and when cooled down, contracts (contraction).
Chapter 7: Getting To Know Plants❖ Plant types: Plants are usually grouped into
• Herbs: Short plants with green and tender stems.
• Shrubs: Plants with hard but not very thick stems. Their stem branches near the base.
• Trees: Tall plants with hard and thick brown stem.
• Creepers: Plants that spread on ground
• Climbers: Plants that take support of neighbouring structures.
• Trees: Tall plants with hard and thick brown stem.
• Creepers: Plants that spread on ground
• Climbers: Plants that take support of neighbouring structures.
Parts of a plant
❖ Stem
• The stem bears leaves, flowers, and fruits.
• It conducts water from roots To all parts of a plant.
• It conducts water from roots To all parts of a plant.
❖ Leaf
• Leaves prepare their food by photosynthesis.
• The leaves lose water by the process of transpiration.
• The arrangement of veins in a leaf is known as leaf venation.
• Leaf venation is of two types - reticulate venation and parallel venation.
• The leaves lose water by the process of transpiration.
• The arrangement of veins in a leaf is known as leaf venation.
• Leaf venation is of two types - reticulate venation and parallel venation.
❖ Root
• Roots absorb water and minerals from the soil
• Roots also anchor the plant firmly To the soil.
• Roots are of two types
• Roots also anchor the plant firmly To the soil.
• Roots are of two types
❖ Flower
• Anther and filament are the parts of a stamen.
• Stigma, style and ovary are the parts of a pistil.
Chapter 8: Body Movements❖ Skeletal system
• The bony framework of our body is called skeleton
• The human skeleton is made up of bones and cartilages.
• Major bones of human body are skull, rib cage, backbone, shoulder bones, and pelvic bones.
• It protects many internal organs and gives shape To the body and helps in movement.
• The human skeleton is made up of bones and cartilages.
• Major bones of human body are skull, rib cage, backbone, shoulder bones, and pelvic bones.
• It protects many internal organs and gives shape To the body and helps in movement.
❖ Movement
• Alternate contraction and relaxation of muscles helps in the movement of bones.
• The muscles work in pairs To move a bone.
• The muscles work in pairs To move a bone.
❖ Joints
• The places where two parts of our body seem To be joined are known as joints. Some types of joints are
Types of Joints | Movement | Example |
Ball and socket joint |
Allows movement in all directions | Shoulder joint |
Pivotal joint |
Allows only rotating movements i.e. One bone rotates over other in a ring fashion. | Neck joint |
Hinge joint |
Allows only back and forth movement | Knee joint |
Fixed joint |
The bones at this joint cannot move. |
Skull joint |
❖ Movement in other animals
• Earthworm - Moves by alternate extension and contraction of the body muscles. It has bristles that help in gripping the ground.
• Snail - Moves with the help of a muscular foot
• Cockroach - Has distinct muscles for moving and also has two pairs of wings.
• Birds - The bones of hind limbs are used for walking and perching and the bones of forelimbs are modified as wings. The bones of birds are hollow and light.
• Fish - Has streamlined body shape, fins and tail that help in movement.
• Snake - Slithers on ground by looping sideways. The bones and muscles help in movement.
Chapter 9: The Living Organisms and Their Surroundings• Snail - Moves with the help of a muscular foot
• Cockroach - Has distinct muscles for moving and also has two pairs of wings.
• Birds - The bones of hind limbs are used for walking and perching and the bones of forelimbs are modified as wings. The bones of birds are hollow and light.
• Fish - Has streamlined body shape, fins and tail that help in movement.
• Snake - Slithers on ground by looping sideways. The bones and muscles help in movement.
❖ Habitat: It is the type of environment where an organism lives.
❖ Adaptations: Specific features that enable a plant or an animal To live in its habitat are known as adaptations.
❖ Biotic components: Living things such as plants and animals in a habitat
❖ Abiotic components: Non-living things such as rocks, soil, air, and water in a habitat
❖ Types of habitat:
• Terrestrial habitat: The examples of terrestrial habitats are deserts, grassland and mountain regions.
• Deserts: Animals are camels, rat, etc and plants is cactus
• Deserts: Animals are camels, rat, etc and plants is cactus
• Adaptations of desert animals:
⚬ Camels have long legs which help them To keep then away from the heat of the sand.
⚬ Also, To minimize the water loss they excrete small amount of urine.
⚬ Also, To minimize the water loss they excrete small amount of urine.
• Adaptations of Cactus:
⚬ It has long roots that go deep inside the soil for absorbing water.
⚬ Its leaves are present in the form of spines To prevent water loss through transpiration.
⚬ Its stem is covered with a thick waxy layer To retain water.
⚬ Its leaves are present in the form of spines To prevent water loss through transpiration.
⚬ Its stem is covered with a thick waxy layer To retain water.
• Mountain regions: Animals commonly found are snow leopards, yak, mountain goat, etc and plants are pines, cedar, etc.
• Adaptations of animals:
⚬ Presence of thick skin or fur To protect themselves from cold
⚬ Cone shaped trees with sloping branches such as pines
⚬ Cone shaped trees with sloping branches such as pines
• Adaptations of Plants:
⚬ Plants are usually cone-shaped with sloping branches. They have needle like leaves that helps in sliding off the rainwater and snow from its surface.
• Grasslands
⚬ Animals commonly found are lion, deer, etc.
⚬ Plants commonly found are grasses
⚬ Plants commonly found are grasses
❖ Aquatic habitat
• Animals commonly found are fish, octopus, squids, etc.
• Fishes have streamlined body. They have gills To use oxygen dissolved in water.
• Fishes have streamlined body. They have gills To use oxygen dissolved in water.
❖ Ponds and lakes
• Animals commonly found are frogs, toads, etc.
• Adaptations:
⚬ Plants have long, hollow and light stems.
⚬ Leaves are narrow or highly divided.
⚬ Animals like frogs and ducks have webbed feet.
⚬ Leaves are narrow or highly divided.
⚬ Animals like frogs and ducks have webbed feet.
❖ Living organisms: An organism is called living if it shows all the seven characteristics – nutrition, respiration, movement, sensitivity, reproduction, excretion and growth.Chapter 10: Motion and Measurement of Distances
❖ Non standard methods of measurement : Hand-span, foot-span, finger width, palm length, the distance of a step,
❖ two parts of the measurement of a quantity are number and unit.
❖ Nowadays, the International system of units (SI) is used as standard units all over the world.
❖ Metre (m) is the SI unit of length.
❖
❖ The length of a curved line can be measured with the help of a thread. Measurement of the thread on a metre scale gives the length of the curved line.
❖ Types of motion:
• Rectilinear motion - When an object moves along a straight line.
• Circular motion - When the distance of the object from a fixed point remains constant.
• Periodic motion - When an object moves To and from about a fixed point.
• Circular motion - When the distance of the object from a fixed point remains constant.
• Periodic motion - When an object moves To and from about a fixed point.
❖ Motion of an object is the change in its position with time.
❖ The fastness or slowness of the movement of an object is determined by measuring the distance travelled with time.Chapter 11: Light, Shadows and Reflection
❖ Types of objects
Transparent objects | Translucent objects | Opaque objects |
Allow light To pass through them. | Allow light To pass through them partially. | Do not allow light To pass through them. |
One can see clearly through transparent objects. | One can see through translucent objects but not very clearly. | One cannot see through opaque objects. |
Do not cast a shadow because they do not block the light. | Cast faint shadows as they block the light partially. | Cast dark shadows as they block light completely. |
❖ Classification of objects by sense of vision
Object/material | See-through | Shadow cast by it | Classification |
Pencil | Not at all | Dark | Opaque |
Water | Fully | No shadow | Transparent |
Butter paper | Partially | Light | Translucent |
❖ A shadow is always grey or dark. It is obtained only on a screen.
❖ A pinhole camera is a simple optical device that forms an image without using a lens or a mirror.
• The image formed by a pinhole camera is real, inverted, and diminished.
• The formation of image in a pinhole camera is a proof of rectilinear propagation of light.
❖ A mirror forms images by the reflection of light. The images formed by mirrors are virtual, erect, and of same size as object.
❖ Left-Right Inversion: The left of an image formed by a plane mirror appears as right and its right appears as left.Chapter 12: Electricity and Circuits
❖ Electric cell: It is a source of electricity. There are two terminals of a cell – Positive (+) and Negative (–).
❖ Electricity is generated in a cell because of chemical reactions that take place inside it.
❖ Electric Bulb: A bulb has a filament and two terminals.
❖ The filament gives off light when an electric current flows through it.
❖ The electric circuit provides a complete path for electricity To pass between two terminals of the electric cell.
❖ In an electric circuit, the direction of current is taken from the positive To the negative terminal of a cell that is connected To the circuit.
❖ A fused bulb does not emit light as No current flows through its filament.
❖ Electric switch: A switch either breaks or connects the circuit.
❖ A torch consists of a cell or a battery, a bulb, and a switch.
❖ Conductors allow the current To flow through it while insulators do not allow the current To flow through it.
❖ Examples of conductors are aluminium, copper, iron, and steel and insulators are plastic, wood, glass, and rubber.
❖ Conductors are used To make electrical wires and insulators are used To cover them.Chapter 13: Fun with Magnets
❖ Magnetite has the property To attract objects made of iron.
❖ The substance that can attract iron, cobalt, or nickel is known as a magnet.
❖ Magnet was discovered by a shepherd named Magnes around 2000 B.C. who lived in Magnesia, Greece.
❖ Materials that get attracted towards the magnets are the magnetic materials.
❖ Materials that do not get attracted towards the magnets are the non-magnetic materials.
❖ There are two poles of a magnet – North Pole (N) and South Pole (S).
❖ A freely suspended bar magnet always aligns along North-South direction.
❖ The direction at a place can be identified with the help of a bar magnet or a magnetic compass.
❖ A magnetic compass consists of a magnetic needle that always comes To rest in the North-South direction.
❖ In older days, sailors found direction by suspending bar magnets.
❖ Like poles always repel each other. Unlike poles always attract each other.
❖ An iron bar becomes a bar magnet when one of the poles of a bar magnet is rubbed on it several times. This is known as touch-stroke method.
❖ A magnet looses its magnetic property when dropped from a height, hammered, or heated.
❖ Magnets can be stored safely as follows.
❖ Magnets should be kept away from cassettes, CDs, mobile, TVs, plastic cards, etc.Chapter 14: Water
❖ Water is essential for life.
❖ Wells, rivers, or lakes are sources of fresh water.
❖ Ocean and sea water is not potable because they dissolve large amount of salt in them.
❖ Water Cycle: The circulation of water between rivers, lands and clouds is known as water cycle.
• The change of water inTo its vapour is known as evaporation.
• The change of vapour back inTo water is known as condensation.
• Fall of water from clouds is known as precipitation or rainfall.
• The change of vapour back inTo water is known as condensation.
• Fall of water from clouds is known as precipitation or rainfall.
• Runoff is the process by which rain water returns back To the river bodies.
❖ Clouds are formed during the process of condensation.
❖ Heavy rain in a short period of time causes flood.
❖ No rain for a long period causes drought.
❖ Most of the potable water (drinking water) becomes available To us as ground water.
❖ There is an immediate requirement To harvest water. The basic idea behind rainwater harvesting is ‘Catch water where it falls’.
❖ In rainwater harvesting method, the stored rainwater is used To recharge ground water.
❖ In rooftop rainwater harvesting system, the rainwater is collected from rooftop in a storage tank. It allows the water To go inTo the pit through pipes. This water seeps and refills the ground water.Chapter 16: Garbage In, Garbage Out
❖ The garbage collected in the garbage trucks is disposed in low lying open areas known as landfill.
❖ To deal with garbage, useful and non-useful components are separated.
❖ The useful components (that rot completely) include fruit or vegetable peels, paper bags, dried leaves, etc. They must be dumped in the green bins.
❖ The non-useful components (that do not rot) include aluminium wrappers, glass pieces, old shoes, plastic bags, etc. They must be dumped in the blue bins.
❖ Composting
• The rotting and conversion of plant and animal waste inTo manure is known as composting.
• Materials such as plastics cannot be converted To less harmful substances by composting.
• The method of preparing compost with the help of red worms is known as vermicomposting.
• Materials such as plastics cannot be converted To less harmful substances by composting.
• The method of preparing compost with the help of red worms is known as vermicomposting.
❖ Recycle of materials
• Materials such as newspaper notebooks, envelopes, etc. can be easily recycled To form useful products.
• Materials such as plastics can cause health hazards and environmental problems. Therefore, the use of plastics should be minimized.
• Materials such as plastics can cause health hazards and environmental problems. Therefore, the use of plastics should be minimized.
❖ Dealing with garbage
• Minimise the use of plastic bags.
• Use jute or paper bags.
• Never burn plastic bags and dried leaves.
• Use vermicomposting To deal with domestic waste.
• Do not waste paper.
Chapter 15: Air around Us• Use jute or paper bags.
• Never burn plastic bags and dried leaves.
• Use vermicomposting To deal with domestic waste.
• Do not waste paper.
❖ Moving air is called wind.
❖ Air occupies empty spaces.
❖ Air is a mixture of many gases.
❖ Composition of air
• Nitrogen -75%
• Oxygen – 21%
• Carbon di oxide – 0.03%
• Water vapour and other gases – 0.07%
❖ Plants prepare their food in the presence of carbon dioxide during the process of photosynthesis.• Oxygen – 21%
• Carbon di oxide – 0.03%
• Water vapour and other gases – 0.07%
❖ During photosynthesis, oxygen is released. Hence, it gets replenished in the atmosphere.
❖ Animals take oxygen and produce carbon dioxide during the process of respiration.
❖ Aquatic animals use air dissolved in water for respiration.
❖ Dust and smoke can be seen as a streak of light when sunlight enters a dark room through a slit.
❖ Windmill generates electricity when wind turns its fan rapidly.
❖ Windmills are also used To draw water from wells and To run flour mills.
❖ Air helps in the flight of birds and insects and in the movement of sailing yachts, gliders, airplane, paper airplane, etc.