7th Class

Coding-Decoding

Coding - Decoding Learning Objectives

What is Coding ? Decoding
Types of Problem

What is Coding - Decoding A ‘code’ is a system of conveying a message through signals. It is method of sending a message between sender and the receiver in such a way that only the sender and the receiver can know its meaning. However ‘Coding’ is done according to a certain pattern in the mind of the sender Therefore, Its meaning can be deciphered by a third person, only if he carefully studies this pattern. This process is called ‘Decoding’. This capability is important in many fields of application. Generally, letters are coded into numbers according to their position in alphabetical order in backward more...

Catgeory: 7th Class

Cubes and Dices

Cubes and Dices Concept of Cubes A cube is a three-dimensional figure which has 8 corners, 6 surfaces and 12 edges. Type I If a cube is painted on all of its surfaces with a colour and then divided into smaller cubes of equal size, then after separation, number of smaller cubes so obtained will be calculated as under: No. of smaller cubes with three surfaces painted = 8 No. of smaller cubes with one surface painted \[= \left( n - 2 \right)~12\] No. of smaller cubes with no surface painted \[={{\left( n - 2 \right)}^{2}}~6\] No. of smaller cubes with no surface painted \[= {{\left( n - 2 \right)}^{3}}\] Where, n = No. of divisions on the surface of the bigger cube \[=\frac{length\,of\,edge\,of\,big\,cube}{length\,of\,edge\,of\,one\,smaller\,cube}\]

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Catgeory: 7th Class

Nutrition

Nutrition Nutrition in Plants All living things need food to survive. Food gives energy to grow, reproduce, move and to work. Nutrition is the process by which an organism obtains its food and utilize them. The nutrition can be categorised mainly into two types namely autotrophic and heterotrophic nutrition. Autotrophic Nutrition Green plants, algae and some bacteria can produce their own food by the process of photosynthesis. The process of photosynthesis occurs only when plants or algae or some bacteria have green pigment, called chlorophyll in their cells. In the process of photosynthesis, the leaves of plants convert water and carbon dioxide into glucose or sugar and oxygen with the help of energy from the sun. Plants take in carbon dioxide from air and water from the soil. Heterotrophic Nutrition The plants which do not contain chlorophyll obtain their food by more...

Catgeory: 7th Class

Fibre to Fabric

Fibre to Fabric Fibre Fibre is a natural or synthetic substance which is used to manufacture the other things. Natural Fibre Natural fibre is obtained from plants and animals. Fibres such as cotton, flax and jute are derived from plants. Fibres such as silk and wool are derived from animals. Plant Fibres The fibres which we get from plants are called plant fibres. Cotton, flax and jute are plant fibres. Cotton: Cotton fibre is obtained from the cotton bolls of the cotton plant. Flax: Flax fibre is soft, lustrous and flexible. It is stronger than cotton fibre but is less elastic. The finer grade of flax fibre is used for producing linen fabrics such as damasks, lace and sheeting. The coarser grades of flax fibre are used for manufacturing twine and rope. Flax fibre also forms the raw material for more...

Catgeory: 7th Class

Physical Chemical Changes

Physical and Chemical Changes All the substances have certain properties such as state (solid, liquid or gas), size, color, smell, temperature, shape, composition and structure etc. When properties of a substance become different, we say that a change has taken place in it. Changes are taking place all around us. Some changes are beneficial to us and some are harmful to us. As for example ripening of fruits is a beneficial change. On the other hand rusting of iron is a harmful change. Type of Changes

Physical changes

Chemical changes

Physical Change Change in the physical properties (such as state, shape, size and colour) of a substance is called physical change. For example, breaking of glass, melting of ice, expanding of balloon, etc. Characteristics of Physical Change

No new substances are formed.
Changes are temporary and can more...

Catgeory: 7th Class

Acids, Bases and Salts

Acids, Bases and Salts Acids Acids are present in things that we eat such as lemon and orange contains citric acid, tomato contains oxalic acid, vinegar contains acetic acid, yoghurt contains lactic acid and frizzy drinks contain carbonic acid. Acids found in foods are mild. Acids such as hydrochloric acid (HCI), sulphuric acid \[({{H}_{2}}S{{O}_{4}})\]and nitric acid \[(HN{{O}_{3}})\]are called mineral acids. They are strong acids. Touching strong acids can cause acid burns. Acids are formed by dissolving oxides of non-metals such as carbon, sulphur and nitrogen in water. The oxides of non-metals are acidic because when dissolved in water they form acids. For example: \[C{{O}_{2}}+{{H}_{2}}O\xrightarrow{{}}{{H}_{2}}C{{O}_{3}}\] \[S{{O}_{3}}+{{H}_{2}}O\xrightarrow{{}}{{H}_{2}}S{{O}_{4}}\] \[3N{{O}_{2}}+{{H}_{2}}O\xrightarrow[{}]{}NO+2HN{{O}_{3}}\] Characteristics of Acidic Substances The acidic substances show the following behaviour:

Taste sour.
Turn blue litmus paper into red.
Corrode metals. Acids react with metals to form a compound known as salts. For more...

Catgeory: 7th Class

Weather, Climate and Adaptations of Animals to Climate

Weather, Climate and Adaptations of Animals to Climate Weather Atmospheric conditions include temperature, rainfall and the speed of the wind. Weather indicates the day to day atmospheric conditions. In addition to this, weather report for a place indicates humidity levels, time of sun rise and sun set. Temperature Temperature is a physical quantity expressing hot or cold. The maximum and minimum atmospheric temperature can be measured with the help of thermometer. Humidity Humidity is the amount of water vapour present in the air. The capacity of the air to hold water vapour increases with temperature. The amount of water vapour present in the air expressed as a percentage of the amount of water needed for saturation at the same temperature is called relative humidity. The relative humidity is measured with an instrument called hygrometer. Rainfall, Snow and Fog The humidity in more...

Catgeory: 7th Class

Wind, Storms and Cyclones

Wind, Storms and Cyclones Wind Moving air is called wind. Wind occurs due to the heating caused by the sun. The unequal heating of different parts of the earth causes the wind to blow. When the wind blows with slow speed it is called breeze. When the wind blows with high speed it is called storm. Air Pressure Air exerts pressure. Like temperature and humidity, air pressure also determines the weather of a place on a particular day. Air pressure can be measured with an instrument called barometer.

Wind is Produced Due to Uneven Heating on the Earth by the Sun Uneven heating on the earth can take place by two situations:

Uneven heating between the equator and the poles of the earth

Maximum heat absorbed by the regions close to more...

Catgeory: 7th Class

Life Processes

Life Processes Respiration Food provides energy to all living organisms. Food is first broken down into simple and soluble molecules. The simple molecules are then carried to all the cells. In cells, these molecules combine with oxygen to produce energy. This process of combination of simple food molecules with oxygen to produce energy is called respiration. Types of Respiration There are two types of respirations: aerobic respiration and anaerobic respiration.

Aerobic respiration

Anaerobic respiration

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Catgeory: 7th Class

Motion and Time

Motion and Time Motion If a body changes its position with time it is said to be in motion. Different Types of Motion Motion has been broadly classified into two groups. They are uniform motion, non-uniform motion. Uniform Motion: If a body travels equal distance in equal interval of time then it is said to be uniform motion. For example, a car travels first 30 kilometres in one hour and next 30 kilometres again in one hour and so on then we say that car has uniform motion. Non-Uniform Motion: If a body travels unequal distance in equal interval of time then it is called non-uniform motion. For example, a car travels first 30 kilometres in one hour and next 30 kilometres in half an hour then we say that, the car has non-uniform motion. Speed The speed of a more...

Catgeory: 7th Class

7th Class

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