PSEB 6th Class Social Science Notes in Punjabi English Medium

Punjab State Board Syllabus PSEB 6th Class Social Science Notes Pdf in English Medium and Punjabi Medium are part of PSEB Solutions for Class 6.

PSEB 6th Class Social Science Notes in English Medium

PSEB 6th Class Social Science Notes Geography: The Earth – Our Habitat

PSEB 6th Class Social Science Notes History: People and Society in the Ancient Period

Social Science Notes for Class 6 PSEB Civics: Community and its Development

PSEB 6th Class Science Notes Chapter 16 Garbage Management and Disposal

This PSEB 6th Class Science Notes Chapter 16 Garbage Management and Disposal will help you in revision during exams.

PSEB 6th Class Science Notes Chapter 16 Garbage Management and Disposal

→ Any substance which is no more useful is called waste.

→ Solid waste is called garbage. It is generated by human activities.

→ Garbage has both useful and non-useful components.

→ There are many types of wastes like industrial waste, domestic waste, agricultural waste, biomedical waste, etc.

PSEB 6th Class Science Notes Chapter 16 Garbage Management and Disposal

→ Two types of garbage or solid waste are biodegradable wastes and non-biodegradable waste.

→ For proper disposal of garbage, we must do segregation before disposing of the garbage. We can do this by using differently colored dustbins.

→ To manage the waste there is the 4R’s i.e. reuse, reduce, recycle, refuse.

→ Some parts of the garbage can be reused.

→ Usually, garbage is collected and thrown in landfills.

→ Composting or vermicomposting can be done of useful components or biodegradable components of garbage.

→ Dry leaves, husk of wheat, and part of crops should not be burnt as they produce lots of smoke and harmful gases.

→ Red worms are good for vermicomposting of vegetable and fruit waste, coffee and tea leaves, weeds, etc. but oily, pickled, salty food, and milk products are not good for red worms.

→ Some types of plastics, paper, glass, and metal can be recycled.

PSEB 6th Class Science Notes Chapter 16 Garbage Management and Disposal

→ Plastics bum with a foul smell and produce lots of harmful gases.

→ Plastic bags cause choking of drains and sewer systems.

→ Plastic bags eaten by animals are the cause of their death.

→ Plastic is useful as things made of them last long.

→ The incineration method releases harmful gases and causes pollution.

→ e-waste includes discarded mobiles or any electronic device.

→ Garbage: The solid waste is called garbage.

→ Dump: A large low-lying area used to dispose of garbage.

→ Landfill: A low-lying area to be filled by garbage is a landfill.

→ Biodegradable Waste: Waste material that can be decomposed by the action of microorganisms into harmless substances.

PSEB 6th Class Science Notes Chapter 16 Garbage Management and Disposal

→ Non-biodegradable Waste: The waste materials that cannot be decomposed easily.

→ Incineration: The process of burning waste in closed containers.

→ Compost: The decomposition of organic material into useful material is compost.

→ Vermi-Composting: The method of preparing compost with the help of red worms is vermicomposting.

→ Gizzard: The teeth like hard structures present in red worms for grinding purposes is called the gizzard.

→ Recycling: The process of using a few materials, again and again, is recycling.

PSEB 6th Class Science Notes Chapter 15 Air Around Us

This PSEB 6th Class Science Notes Chapter 15 Air Around Us will help you in revision during exams.

PSEB 6th Class Science Notes Chapter 15 Air Around Us

→ All living things require air to live.

→ Air is present everywhere around us however we cannot see the air.

→ Our earth is surrounded by a thin layer of air that extends upto many kilometres above the surface of the earth. This is known as the atmosphere.

→ Air is made up of water vapours, Oxygen, Nitrogen, Carbon dioxide, dust, and smoke.

PSEB 6th Class Science Notes Chapter 15 Air Around Us

→ Nitrogen and Oxygen are the main constituents of air and are present in large quantities.

→ In the air, nitrogen is 78% and oxygen is only 21%.

→ Oxygen is required for burning.

→ Carbon dioxide is a greenhouse gas.

→ The balance of Oxygen and Carbon dioxide in the atmosphere is maintained by the presence of living organisms (man, animals) and plants.

→ Carbon dioxide is used by plants for producing food by photosynthesis. They release oxygen.

→ Oxygen is consumed by animals and humans for respiration. They produce carbon dioxide.

→ Carbon dioxide is used as a fire extinguisher because carbon dioxide does not support g burning.

→ Air can be compressed and it also exerts pressure.

PSEB 6th Class Science Notes Chapter 15 Air Around Us

→ Moving air is called wind.

→ Moving air has the power to rotate a windmill which produces electricity.

→ Windmills are very useful as they produce electricity.

→ Air helps in the dispersal of seeds, pollens, and movement of sailing boats, yachts, gliders, aeroplanes, etc.

→ Dispersal of pollens is known as pollination.

→ Ozone present in the upper layer of the atmosphere protects us from the UV rays of the sun.

→ Air: It is a mixture of many gases like nitrogen, oxygen, carbon dioxide, water vapours, etc.

→ Wind: The moving air is wind.

PSEB 6th Class Science Notes Chapter 15 Air Around Us

→ Windmill: A device that is being rotated by air and is used for producing electricity.

→ Atmosphere: The thin blanket of air surrounding the earth constitutes the atmosphere.

PSEB 6th Class Science Notes Chapter 14 Water

This PSEB 6th Class Science Notes Chapter 14 Water will help you in revision during exams.

PSEB 6th Class Science Notes Chapter 14 Water

→ Water is a vital resource and is considered a boon to live.

→ Water is present all over the earth.

→ Around the 3/4th part of the earth, the surface is covered with water.

→ The human body consists of 70% of water.

PSEB 6th Class Science Notes Chapter 14 Water

→ We need water for our daily activities and for producing other things.

→ Two main sources of water are surface water and groundwater.

→ Water exists in three states i.e. solid, liquid, and gas.

→ We get water from ponds, lakes, rivers, wells, etc.

→ Sea or Ocean water is salty. It is not fit for drinking and for domestic, agricultural, and industrial needs.

→ As water is a vital resource so it must be conserved.

→ Judicious use of water and saving it is conservation of water.

→ Rainwater is a pure form of water and is safe for drinking.

→ Rainwater harvesting is a technique that conserves water by storage of rainwater. This water can be reused for different useful purposes.

→ The water cycle is a cyclic process in which water is circulated between the earth and the atmosphere.

→ Ocean water supplies water to the water cycle and thus plays an important role.

→ Water from oceans, lakes, wet clothes and plants gets evaporated.

PSEB 6th Class Science Notes Chapter 14 Water

→ Clouds are just the condensation of evaporated water in the air.

→ Clouds cause rains and water returns to earth, oceans, lakes, etc.

→ Snow on mountains melts and water runs into rivers.

→ Water is also absorbed by the ground and becomes available to us as groundwater.

→ Heavy rains and no rains cause too many problems.

→ Heavy rains cause floods which destroy lives and properties.

→ Overflow of water in a large amount beyond its normal limits is known as a flood.

→ A flood is a natural disaster.

→ No rain or very little rain in a region is caused by the drought.

→ In drought conditions availability of food, fodder, and water become negligible.

→ With the increase of population, industries, and agriculture also increase which lay stress on the use of water.

PSEB 6th Class Science Notes Chapter 14 Water

→ Melting: The process of conversion of solid into liquid is called melting.

→ Freezing: The process of converting liquid into solid is called freezing.

→ Evaporation: The process of converting liquid into its vapours is called evaporation.

→ Transpiration: The process by which plants lose their water in the air is called transpiration.

→ Condensation: The process of conversion of water vapours into water is called condensation.

→ Precipitation: Falling of water in the form of rain and snow is called precipitation.

→ Clouds: The condensed water droplets join together to form clouds.

PSEB 6th Class Science Notes Chapter 14 Water

→ Water cycle: The evaporation of water to air, formation of clouds by condensation, and falling of rain on the earth constitutes the water cycle in nature.

→ Rainwater harvesting: Collection of rainwater for use at a time when it is not available otherwise is rainwater harvesting.

PSEB 6th Class Science Notes Chapter 13 Fun with Magnets

This PSEB 6th Class Science Notes Chapter 13 Fun with Magnets will help you in revision during exams.

PSEB 6th Class Science Notes Chapter 13 Fun with Magnets

→ Magnetite is a natural magnet.

→ Some rocks have the property of attracting pieces of iron and these are called natural magnets.

→ Magnet has the property of attracting iron, cobalt, and nickel. Such substances are called magnetic substances.

→ Every magnet has two poles:

  • North Pole
  • South pole

→ A freely suspended magnet sets itself in a North-South direction.

PSEB 6th Class Science Notes Chapter 13 Fun with Magnets

→ Unlike (opposite) poles of two magnets attract each other whereas like poles repel each other.

→ Man-made magnets are called artificial magnets.

→ Magnets made from iron pieces are called artificial magnets.

→ Magnets are of different shapes such as Bar magnet, Horseshoe shaped (U-shaped) magnet, cylinderical magnet, or spherical magnet.

→ Compass is used to find direction.

→ When a magnet is brought near a compass, its needle gets deflected.

→ On heating a magnet, striking it with a hammer, or dropping it from a height it loses its property of magnetism.

→ If a magnet is not properly stored then it loses its property with time.

→ To store bar magnets with safety the opposite poles of two magnets are placed facing each other.

→ The magnet should be kept away from cassettes mobiles, TVs, CDs, and computers, etc.

→ Compass: Compass is a device that is needed to determine direction.

PSEB 6th Class Science Notes Chapter 13 Fun with Magnets

→ Magnet: Such substances which have the property of attracting iron are called magnets.

→ Magnetite: Magnetite is a natural magnet that was first discovered by a Shepherd named Magnus.

→ North pole: That end of a freely suspended magnet that points towards the geographical north direction is called its North pole.

→ South pole: That end of a freely suspended magnet that points towards the geographical south direction is called its South pole.

PSEB 6th Class Science Notes Chapter 12 Electricity and Circuits

This PSEB 6th Class Science Notes Chapter 12 Electricity and Circuits will help you in revision during exams.

PSEB 6th Class Science Notes Chapter 12 Electricity and Circuits

→ An electric cell is a source of electric energy.

→ The electric cell has two terminals: one positive terminal (+) and the other negative terminal (-).

→ The electric bulb has one filament which is connected to its terminals.

→ On passing the electric current, the bulb begins to glow.

→ In a closed electric circuit, the electric current passes from one terminal of the electric cell to the other terminal.

PSEB 6th Class Science Notes Chapter 12 Electricity and Circuits

→ The switch is a simple device that is used to either break the electric circuit or to complete it.

→ Materials that allow an electric current to pass through them, are called conductors.

→ Materials that do not allow an electric current to pass through them are called insulators.

→ Light-emitting thin wire of the bulb is called filament of the bulb.

→ On the breaking of filament, the bulb becomes fused.

→ The complete path of electric current is called an Electric circuit.

→ Bulb: It is a simple device that gives out light on passing an electric current through it.

→ Electric conductor: Materials that allow current to pass through them are called electric conductors.

→ Electric cell: Electric cell is a source of electricity. The chemicals stored in it produce an electric current.

PSEB 6th Class Science Notes Chapter 12 Electricity and Circuits

→ Electric circuit: The path of current from one terminal to another terminal, through a switch, bulb, and switch, is called an electric circuit.

→ Filament: A small thin metallic wire (Tungsten) inside a bulb that glows when current is allowed to pass through it, is called a filament.

→ Insulators: Materials that do not allow current to pass current through them are called insulators.

→ Switch: A simple device that is used to break or complete a circuit is called a switch.

→ Terminal: The point of entering or exit of electric current is called terminal.

→ An electric cell has two terminals:

  • Positive terminal
  • Negative terminal.

PSEB 6th Class Science Notes Chapter 11 Light Shadows and Reflections

This PSEB 6th Class Science Notes Chapter 11 Light Shadows and Reflections will help you in revision during exams.

PSEB 6th Class Science Notes Chapter 11 Light Shadows and Reflections

→ Light is a form of energy that enables us to see the things around us.

→ A source of light can be either natural or artificial as for example Sun, Moon, Stars CFL, Candle, and LED.

→ Light ordinarily travels along a straight path.

→ Opaque objects do not allow light to pass through them and the objects lying on the other side of it cannot be seen.

PSEB 6th Class Science Notes Chapter 11 Light Shadows and Reflections

→ Transparent objects allow light to pass through them and we can see through these objects clearly.

→ Translucent objects allow light to pass through them partially and the objects lying on another side of these objects are not seen clearly.

→ Shadows are formed when an opaque object comes in the path of light.

→ A pinhole camera can be made with simple materials and can be used to obtain the image of the Sun and other bright (luminous) objects. This image is inverted and small in size.

→ Reflection from the mirror gives us clear images.

→ Luminous Object: Such objects have light of their own and give out light.

→ Non-Luminous Object: Such object which has no light of its own and becomes luminous from light emitted by other luminous objects.

→ Light: It is a form of energy that enables us to see the surrounding objects but light itself is not seen.

→ Source of light: Such luminous bodies which have the light of their own and which emit light as for example candle CFL etc. The source light may either be a Natural or Artificial source.

PSEB 6th Class Science Notes Chapter 11 Light Shadows and Reflections

→ Transparent objects: Such objects through which light can pass and on the other side of which we can see clearly are called transparent objects. Examples are Air, water, glass, etc.

→ Opaque objects: Those objects which do not allow light to pass through them and the objects on the other side of which cannot be seen are called opaque objects. Examples are Cardboard sheets, wood, metal, and rubber, etc.

→ Translucent objects: Those objects through which light can pass but partially and the objects lying on the other side of which are not seen clearly are called translucent objects. Examples are Tissue paper, thin cloth, oiled paper, etc.

→ Shadow: When an opaque object is placed in the path of the light rays coming from a source of light then light cannot pass through and a black region is formed on the other side of the opaque body. This black region where no light is received is called the shadow. The size of the shadow can be small or large.

→ Sundial: It is an instrument that shows time with the help of shadows formed by sunlight.

→ Solar Eclipse: When the moon while revolving around the earth comes in such a situation that the moon is in between the earth and the sun and all the three are in a straight line then the shadow of the sun is formed on the earth, a solar eclipse is said to occur.

→ Lunar Eclipse: When the earth comes in between the sun and moon and all the three are in a straight line and the shadow of the moon is formed on the earth; then the lunar eclipse is said to occur.

PSEB 6th Class Science Notes Chapter 11 Light Shadows and Reflections

→ Pinhole camera: It is an instrument in which the inverted and small-sized image of a stationary object such as a building or tree is formed. It is constructed on the principle of propagation of light in a straight line.

→ Mirror: Any smooth and polished surface which changes the path of light rays falling on it, is called a mirror.

→ Reflection of light: When light falls on a mirror and light falling on it is sent back into the same medium in a particular direction, then this phenomenon of change of direction of the path of light is called reflection of light. Reflection of light is of two types:

  • Regular reflection
  • Irregular reflection

→ Regular reflection: When light falls on a smooth plane mirror or a polished surface then a reflection of light takes place in a regular manner. This reflection of light is called regular reflection.

PSEB 6th Class Science Notes Chapter 11 Light Shadows and Reflections

→ Irregular reflection: When light falls on any rough or uneven surface than light rays after reflection gets scattered. This reflection of light is called irregular reflection. We can see the various objects around us due to this reflection.

PSEB 6th Class Science Notes Chapter 10 Motion and Measurement of Distances

This PSEB 6th Class Science Notes Chapter 10 Motion and Measurement of Distances will help you in revision during exams.

PSEB 6th Class Science Notes Chapter 10 Motion and Measurement of Distances

→ Measurement is a comparison of an unknown quantity with a known fixed quantity of the same kind.

→ Different modes of transport are used to move from one place to another.

→ Earlier cubit, hand span, or foot were used to measure the lengths or distances. Measurements made with them were not accurate.

→ The system of units used is known as the International System of Unit (S.I. Units) and is accepted all over the world.

PSEB 6th Class Science Notes Chapter 10 Motion and Measurement of Distances

→ The S.I. unit of length is meter.

→ Change in the position of an object with respect to things in the surroundings is called motion.

→ The motion of an object in a straight line is called linear motion.

→ In a circular motion, the object moves in a circular path and its distance from a fixed point (centre) always remains the same.

→ A motion that repeats itself after a fixed interval of time is called Periodic motion.

→ The fixed amount of known quantity is called unit.

→ The standard unit of length is a meter.

→ Distance: It is a measurement of length between two points.

→ Measurement: The comparison of an unknown quantity with some known quantity of the same kind.

→ Unit: The known fixed quantity taken as standard for comparison.

→ Odometer: A device fitted in motor vehicles to measure the distance covered by the vehicle.

PSEB 6th Class Science Notes Chapter 10 Motion and Measurement of Distances

→ Motion: When an object changes its position as compared to the surroundings with the passage of time, then the object is said to be in motion.

→ Linear Motion: The motion of an object in a straight line.

→ Circular motion: The motion of an object in a circular path, is called circular motion.

→ Periodic motion: When an object repeats its motions after a fixed interval of time, its motion is called periodic motion.

PSEB 6th Class Science Notes Chapter 9 The Living Organisms and Their Surroundings

This PSEB 6th Class Science Notes Chapter 9 The Living Organisms and Their Surroundings will help you in revision during exams.

PSEB 6th Class Science Notes Chapter 9 The Living Organisms and Their Surroundings

→ Different types of living organisms are present everywhere.

→ All living beings have some common characteristics.

→ They need food, respond to stimuli, respire, excrete, grow, reproduce and show movements.

→ The surroundings where organisms live are called a habitat.

PSEB 6th Class Science Notes Chapter 9 The Living Organisms and Their Surroundings

→ Habitat may be terrestrial or aquatic or aerial/arboreal. Deserts, mountains, and grasslands are examples of terrestrial habitats. Oceans, ponds, and lakes are examples of aquatic habitats.

→ Organisms having terrestrial habitat are called terrestrial organisms whereas organisms having aquatic habitat are known as aquatic organisms.

→ Plants having terrestrial habitat are called terrestrial plants whereas plants having aquatic habitat are known as aquatic plants.

→ Animals having terrestrial habitats are called terrestrial animals whereas animals having aquatic habitat are known as aquatic animals.

→ All types of habitats have two main components: biotic and abiotic.

→ Biotic components are all living things like plants, animals, human micro-organisms.

→ Abiotic components include all non-living things like rocks, soil, air, water, sunlight.

→ Abiotic factors or components change over thousands of years.

→ The ability of the living things to adjust themselves to their surroundings is called Adaptation.

PSEB 6th Class Science Notes Chapter 9 The Living Organisms and Their Surroundings

→ Organisms i.e. plants and animals adapt differently to live better in different habitats.

→ Rats and snakes stay in burrows deep in the sand to stay away from the intense heat.

→ Cactus is a desert plant that has spines to reduce the loss of water from leaves through transpiration.

→ Trees in the mountain regions are normally cone-shaped having sloping branches and needle-like leaves.

→ Animals have thick skin or fur to protect them from the cold of mountainous regions.

→ Lion, deer, or other animals are adapted to live in grasslands.

→ Squids and octopuses are sea animals. Their habitats are deep-sea (sea bed). They make their body streamlined while swimming.

→ Aquatic plants can be floating, totally submerged, or partially submerged type.

→ A frog is an animal that can live both on land and in water. Its body is adapted to both types of abiotic factors.

→ A cloud grows in size, moves from one place to another but it is a non-living thing.

PSEB 6th Class Science Notes Chapter 9 The Living Organisms and Their Surroundings

→ Some animals go into a state of long sleep during winter for survival and this winter sleep is called Hibernation.

→ Cell: The basic unit of life is called a cell.

→ Unicellular Organisms: Organisms that are made of only one cell.

→ Multicellular Organisms: Organisms that are made of many cells.

→ Stimulus: Living things respond to immediate and long-term changes in their environment.

→ Adaptations: The presence of specific features and habits, which enable a plant or an animal to live in a particular habitat, is called adaptation.

→ Habitat: The surroundings where plants and animals live, are called their habitat.

→ Biotic Component: The living components of habitat are biotic components, e.g. plants, animals.

→ Xerophytes: The plants which grow and propagate in deserts, e.g. cactus.

→ Hydrophytes: The plants which grow and propagate in water.

→ Photosynthesis: The process of manufacturing food by green plants with the help of water, carbon dioxide, sunlight, and chlorophyll.

→ Breathing: Taking in and releasing out air from the body is called breathing.

PSEB 6th Class Science Notes Chapter 9 The Living Organisms and Their Surroundings

→ Respiration: The process of exchange of carbon dioxide and oxygen is called respiration.
(or)
The process of taking oxygen in, combining it with food, and throwing out carbon dioxide and water vapour is called Respiration.

→ Excretion: The process by which waste products are removed from the body of organisms.

→ Producers: Organisms that can manufacture their own food. Examples are all types of green plants.

→ Consumers: Organisms that cannot manufacture their own food but consume food prepared by green plants or other organisms.

→ Predators: Some strong animals that make weaker animals their prey are called predators.

PSEB 6th Class Science Notes Chapter 9 The Living Organisms and Their Surroundings

→ Decomposers: Microorganisms that feed on dead plants and animals and break them into simpler substances.

→ Scavengers: Animals that feed on dead animals.

PSEB 6th Class Science Notes Chapter 8 Body Movements

This PSEB 6th Class Science Notes Chapter 8 Body Movements will help you in revision during exams.

PSEB 6th Class Science Notes Chapter 8 Body Movements

→ Movement is a change in the position of any part of the body of an organism.

→ Locomotion is the movement of the whole body of an organism from one place to another.

→ Animals show locomotion and other types of movements but plants do not locomotion though they show some other types of movements.

→ Walking by man, swimming by fishes, running by horse, crawling by a snake, jumping by grasshopper, and flying by birds, etc. are different modes of locomotion.

PSEB 6th Class Science Notes Chapter 8 Body Movements

→ The purpose of locomotion by animals is to find water, food, shelter, and protect themselves from enemies.

→ The framework made up of bones that give support to the body is known as the skeleton.

→ Bones are hard and rigid whereas cartilage is smooth and flexible.

→ The human skeleton comprises bones and cartilages.

→ The human body has 300 bones at the time of birth.

→ The adult human body has 206 bones.

→ The rib cage is made up of ribs, backbone, and chest bone. It protects the internal parts of the body.

→ Skull encloses protects the brain.

→ A Joint is a place where bones meet together.

→ The ligament is an elastic tissue that connects bones together.

→ The movement of the body depends upon the contraction of muscles. These muscles always work in pairs.

→ Gait is the pattern of movement of limbs of animals.

PSEB 6th Class Science Notes Chapter 8 Body Movements

→ The earthworm moves by contraction and extension of the muscles of its body.

→ A snail moves with the help of a large sticky muscular foot.

→ A cockroach can walk, run. climb and fly.

→ Forelimbs of birds are modified into wings that help in flight.

→ The body of fish is streamlined and it moves by fins placed laterally on its body.

→ Birds have streamlined bodies and hollow lightweight bones which help them during g flight.

→ Snakes move by creeping on their belly.

→ Different types of joints allow movements in different directions.

→ Our body has many joints – The ball and socket joint, the Hinge joint, the Fixed joint, and the Pivotal joint.

→ The ball and socket joint allows the movement in a circular form or in all directions.

→ The hinge joint allows back and forth movement.

→ The pivotal joint allows the movement forward and backward, right or left. The joint of the neck and head is an example.

→ Fixed joints are immovable.

PSEB 6th Class Science Notes Chapter 8 Body Movements

→ X-ray helps in counting the number of bones and studying the shape of bones in all bodies.

→ Movement: is a change in the position of any part of the body of an organism.

→ Locomotion: is the movement of the whole body of an organism from one place to another.

→ Bone: It is the part of the skeleton which is hard in nature.

→ Joint: A joint is a part of the body where two or more bones meet to allow some type of movement.

→ Cartilage: Smooth, thick, and flexible tissue found in joints.

→ Fixed Joints: The joints at which bones cannot move is known as fixed joint.

→ Moveable Joints: The joints where the movement of the bones is possible are called movable joints.

→ Skeleton: The framework of the body that gives support and shape to the body.

→ Streamlined body: A body that tapers at both ends is called a streamlined body.

→ Tendon: The strong, fibrous tissue which attaches muscles to bones is called a tendon.

→ Ligaments: Strong, flexible tissue which connects two bones.

PSEB 6th Class Science Notes Chapter 8 Body Movements

→ Pelvis: The large bony bowl formed by the fusion of hip bones and the last two parts of the backbone is known as the pelvis.

→ Pectoral Girdle: The girdle that supports the bones of the arm is called the pectoral girdle.

→ Pelvic Girdle: The girdle that supports the bones of the legs is called the pelvic girdle.

→ Vertebrae: These are the small ring-shaped bones present in the backbone.

→ Dislocation: The dislodging of bones at the joints from their normal positions is called dislocation.