Articles

There are many professionals who provide their services against payment of their fee. Thus, all types of services are special skills provided in exchange of payments. Health, education, law, governance and recreation etc. require professional skills.

All economic activities namely primary, secondary, tertiary and quaternary, revolve around obtaining and utilising resources necessary for survival.

Human activities which generate income are known as economic activities. Economic activities are broadly grouped into primary, secondary, tertiary and quaternary activities.

The people of a country are its real wealth. It is they, who are the actual resources and make use of the country’s other resources and decide its policies. Ultimately a country is known by its people.

The Last Lesson is set in the days of the Franco-Prussian War (1870-1871) in which France was defeated by Prussia led by Bismarck. Prussia then consisted of what now are the nations of Germany, Poland and parts of Austria. In this story the French districts of Alsace and Lorraine have passed into Prussian hands.

The amount of carbon present in the earth’s crust and in the atmosphere is quite meagre. The earth’s crust has only 0.02% carbon in the form of minerals (like carbonates, hydrogen-carbonates, coal and petroleum) and the atmosphere has 0.03% of carbon dioxide. In spite of this small amount of carbon available in nature, the importance of carbon seems to be immense.

Elements can be classified as metals or non-metals on the basis of their properties.

All organisms such as plants, animals, microorganisms and human beings as well as the physical surroundings interact with each other and maintain a balance in nature.

An electric current-carrying wire behaves like a magnet. Electricity and magnetism are linked to each other.

Electricity has an important place in modern society. It is a controllable and convenient form of energy for a variety of uses in homes, schools, hospitals, industries and so on.

The human eye uses light and enables us to see objects around us. It has a lens in its structure.

An object reflects light that falls on it. This reflected light, when received by the eyes, enables to see things.

Reproductive processes give rise to new individuals that are similar, but subtly different. Some amount of variation is produced even during asexual reproduction. The number of successful variations are maximised by the process of sexual reproduction.

Organisms look similar because their body designs are similar. If body designs are to be similar, the blueprints for these designs should be similar. Thus, reproduction at its most basic level will involve making copies of the blueprints of body design.

In animals, control and coordination are provided by nervous and muscular tissues.

The biological process involved in the removal of these harmful metabolic wastes from the body is called excretion. Different organisms use varied strategies to do this.

Blood transports food, oxygen and waste materials in our bodies. Blood consists of a fluid medium called plasma in which the cells are suspended. Plasma transports food, carbon dioxide and nitrogenous wastes in dissolved form.

The food material taken in during the process of nutrition is used in cells to provide energy for various life processes. Diverse organisms do this in different ways - some use oxygen to break-down glucose completely into carbon dioxide and water, some use other pathways that do not involve oxygen.

When we walk or ride a bicycle, we are using up energy. Even when we are not doing any apparent activity, energy is needed to maintain a state of order in our body.

The maintenance functions of living organisms must go on even when they are not doing anything particular. Even when we are just sitting or even if we are just asleep, this maintenance job has to go on. The processes which together perform this maintenance job are life processes.

Acids are sour in taste and change the colour of blue litmus to red, whereas, bases are bitter and change the colour of the red litmus to blue.

Whenever a chemical change occurs, a chemical reaction has taken place.

Sound is produced by vibrations. Vibration refers to the periodic to and fro motion (oscillations) of an object. Pulling a stretched string or striking a metal object makes them vibrate, which produces sound.

A force can make an object move from rest, change the speed and direction of motion of a moving object, and can even change the shape of an object.

Life begins when a single cell divides itself several times to give rise to a large number of cells. These cells gradually form the skin (protection), muscles (movement), bones (support), nerves (control and coordination), and all other organs.

Matter consists of tiny particles called atoms. In 1808, John Dalton proposed his atomic theory. It was based on scientific experiments of that time. He proposed that all matter is composed of indivisible particles called atoms.

While there are billions of planets in the universe, Earth is the only one where life, as we know today, exists and thrives in all its forms.

The living beings are termed as the biotic components and non-living things as the abiotic components of a habitat.

The bright portion of the Moon decreases from a full circle to a half circle in about a week.

Spherical mirrors are a common type of curved mirrors which are shaped like a part of a hollow glass sphere. Mirrors, whose reflecting surfaces are spherical are called spherical mirrors.

When salt and sugar are mixed with water, a uniform mixture is formed, whereas when chalk powder or sand, or sawdust is mixed with water, the components are not evenly distributed. Such mixtures are known as non-uniform mixtures.

When two or more substances are mixed, where each substance retains its properties, it is called a mixture. The individual substances that make up a mixture are called its components.

A constituent particle is the basic unit that makes up a larger piece of a substance or material. The spaces between the particles are known as interparticle spaces.

When we carry a bag, we feel its weight because of the force of gravity acting on our shoulders. The weight of the bag with narrow straps acts on a smaller area of our shoulders, whereas the weight of the bag with broad straps is spread out over a larger area of our shoulders.

In everyday life, we come across many situations where a force is applied, for example, opening a drawer, stretching a rubber band, a fielder stopping a ball, kicking a football, applying brakes on a moving bicycle, rolling a chapati, or turning the steering handle of an auto rickshaw.

When the current flows, the compass needle gets deflected from its original direction. When the current stops, the needle returns to its original direction.

There was a boy called Mario who loved to have lots of friends. He showed off a lot, always talking about how many friends he had at school, and how he was so friendly with everyone.

May my friendships always be
The most important thing to me.

Gajaraj, the elephant, lived in the best booth of the royal stables. The king was fond of Gajaraj, and he had ordered that the elephant should be well looked after.

Mr Raven was perched upon a limb,
And Reynard the Fox looked up at him;
For the Raven held in his great big beak,
A morsel the Fox would go far to seek.

Rama Natha was the son of a rich landlord. His father left him large tracts of land when he died. But Rama Natha did not spend even one day looking after his land.

As per the World Health Organization (WHO), health is defined as a state of complete physical, mental, and social well-being, and not merely the absence of disease.

The human eye can only see objects that are above a certain size. For a long time, many tiny things around us remained unknown.

The Earth spins (or rotates) on its own axis in space. The Earth’s axis of rotation passes through its geographic North Pole and the South Pole. The Earth completes one rotation in about 24 hours.

The Sun gives out or emits its own light and is the main source of natural light on the Earth. Stars, lightning, natural fire, and certain animals also emit their own light.

plants require both sunlight and water for their growth.

Life processes such as nutrition, circulation, respiration, excretion, and reproduction are essential for the survival of living beings. These processes are collectively called life processes.

Humans got interested in keeping track of time long ago. They started noticing that many events in nature repeat themselves after definite intervals of time.

There are three ways in which heat is transferred from one place to another - conduction, convection, and radiation.

The journey of life of a human can be divided into different stages - infancy, childhood, adolescence, adulthood, and old age. Each person experiences these stages at their own pace, and the duration of each stage may vary from one individual to another.