...You don’t see many birds in winter. Most have left your area. Those that stay are not as active. Activity uses energy that is needed to keep warm. The worst problems for birds in winter are getting enough heat and holding on to the heat once it is made. These are problems for all birds. But it is especially true for very small ones. They cannot find enough food. The weather stays so cold for so long that they cannot eat enough to keep alive. But birds have many ways of fighting the cold.

You shiver to keep warm. The heat that you make is made mostly in your muscles. The muscles make more heat when they are active. So one way of keeping warm is to move about, use your muscles. Another way is to shiver. When your body needs heat, the muscles tighten and loosen quickly. They become active. Just as you shiver to keep warm, so do birds.

How many nostrils do you have? Four. Two you can see, two you can’t. This discovery came from observing how fish breathe. Fish get their oxygen from water. Most of them have two pairs of nostrils, a forward-⁠facing set for letting water in and a pair of "exhaust pipes" for letting it out again. The question is, if humans evolved from fishes, where did the other pair of nostrils go. The answer is that they migrated back inside the head to become internal. To do this they somehow had to work their way back through the teeth.

Similar gaps between the teeth can also be seen at an early stage of the human birth. When they fail to join up, the result is a cleft palate. So one ancient fish explains two ancient human mysteries. The most recent research on noses, incidentally, shows that we use each of our two external nostrils to detect different smells.

Antarctica is the driest place on Earth. Parts of the continent have seen no rain for two million years. A desert is technically defined as a place that receives less than 10 inches of rain a year. The Sahara gets just 1 inch of rain a year.

As well as the driest place on Earth, Antarctica can also claim to be the wettest and the windiest. Seventy percent of the world’s fresh water is found there in the form of ice, and its wind speeds are the fastest ever recorded. The unique conditions in the Dry Valleys of Antarctica are caused by so-⁠called katabatic winds. These occur when cold, dense air is pulled downhill simply by the force of gravity. Though Antarctica is a desert, these completely dry parts of it are called, somewhat ironically, oases. They are so similar to conditions on Mars that NASA used them to test the Viking mission.

The highest mountain is located on Mars. The giant volcano Mount Olympus is the highest mountain in the solar system and in the known universe. At 14 miles and 388 miles across, it is almost three times the height of Mount Everest and so wide that its base would cover Arizona, or the whole of the area of the British Isles. The crater on the top is around 45 miles wide and over nearly 2 miles deep, easily big enough to swallow London.

We traditionally measure mountains by their height. If we measured them by their size, it would be meaningless to isolate one mountain in a range from the rest. That being so, Mount Everest would dwarf Olympus Mons. It is part of the gigantic range which is nearly 1,500 miles long.

The ostrich is the bird that lays the smallest egg for its size. Although it is the largest single cell in nature, an ostrich egg is less than 2 per cent of the weight of the mother. A wren’s egg, by comparison, is 13 per cent of its weight. The largest egg in comparison with the size of the bird is that of the Little Spotted kiwi. Its egg accounts for 26 per cent of its own weight.

An ostrich egg weighs as much as twenty-⁠four hen’s eggs; to soft-⁠boil one takes forty-⁠five minutes. Queen Victoria tucked into one for breakfast and declared it among the best meals she had ever eaten. The largest egg laid by any animal  — including the dinosaurs  — belonged to the elephant bird of Madagascar, which became extinct in 1700. It was ten times the size of an ostrich egg, nine litres in volume and the equivalent of 180 chicken’s eggs.

Despite its status as a proverbial fact, a goldfish’s memory isn’t a few seconds long. Research demonstrated beyond reasonable doubt that goldfish have a memory-⁠span of at least three months and can distinguish between different shapes, colours and sounds. They were trained to push a lever to earn a food reward; when the lever was fixed to work only for an hour a day, the fish soon learned to activate it at the correct time. A number of similar studies have shown that farmed fish can easily be trained to feed at particular times and places in response to an audible signal.

Goldfish don’t swim into the side of the bowl, not because they can see it, but because they are using a pressure-⁠sensing system called the lateral line. Certain species of blind cave fish are able to navigate perfectly well in their lightless environment by using their lateral line system alone.

Half the human beings who have ever died, perhaps as many as 45 billion people, have been killed by female mosquitoes. Mosquitoes carry more than a hundred potentially fatal diseases including malaria, yellow fever and elephantiasis. Even today, they kill one person every twelve seconds. Amazingly, nobody had any idea that mosquitoes were dangerous until the end of the nineteenth century. In 1877, the British doctor Sir Patrick Manson proved that yellow fever was caused by mosquito bites.

Seventeen years later it occurred to him that malaria might also be caused by mosquitoes. He encouraged his pupil Ronald Ross to test the hypothesis. Ross was the first person to show how female mosquitoes transmit the parasite. Manson went one better. To show that the theory worked for humans, he infected his own son  — using mosquitoes carried in the diplomatic bag from Rome.

Chameleons don’t change colour to match the background. They change colour as a result of different emotional states. Chameleons change colour when they beat another chameleon in a fight. They change colour when a member of the opposite sex steps into view and they sometimes change colour due to fluctuations in either light or temperature.

A chameleon’s skin contains several layers of specialised cells. Altering the balance between these layers causes the skin to reflect different kinds of light, making chameleons a kind of walking colour-⁠wheel. It’s odd how persistent the belief that they change colour to match the background is. The myth first appears in the work of a minor Greek writer of entertaining stories and potted biographies. Aristotle, far more influential and writing a century earlier, had already, quite correctly, linked the colour-⁠change to fear. But it’s come back with a vengeance since and to this day is perhaps the only thing most people think they ‘know’ about chameleons.

Who invented the steam engine? Heron from Egypt. Heron lived in Alexandria and is best known as a mathematician and geometer. Unfortunately for Heron, no one was able to see its practical function, so it was considered nothing more than an amusing novelty. Amazingly, had Heron but known it, the railway had already been invented 700 years earlier.

The principle of railways was then completely forgotten about for almost another 500 years, until people had the idea of using them in mines in the fourteenth century. The historian Arnold Toynbee wrote a brilliant essay speculating what would have happened if the two inventions had been combined to create a global Greek empire, based on a fast rail network. Heron also invented the vending machine  — for four drachmas you got a shot of holy water  — and a portable device to ensure that no one else could drink the wine you brought along to a bottle party.

Is French toast from France? Yes and no. Dipping bread in eggs and frying it is a pretty universal solution to making stale bread go further. The French certainly had a medieval version and this later became a name that has been enthusiastically adopted for the de luxe versions. The earliest recorded recipe for the dish occurs in the work of the Roman cook in the first century AD. In his book The Art of Cooking, he writes, rather casually, that it’s just another sweet dish.

However, the dish was also sometimes referred to as ‘Poor Knights of Windsor’. One theory offered in explanation is that the most expensive part of a medieval banquet was dessert  — spices and nuts were costly imports. Although titled, not all knights were rich, so a dish of fried eggy-⁠bread served with jam or honey would have fulfilled the requirements of etiquette without breaking the bank.

Champagne was not invented in France. It may come as surprise  — even an outrage  — to them but champagne is an English invention. As anyone who has made their own ginger beer knows, fermentation naturally produces bubbles. The problem has always been controlling it. The English developed a taste for fizzy wine in the sixteenth century, importing barrels of green, flat wine from Champagne and adding sugar and molasses to start it fermenting. They also developed the strong coal-⁠fired glass bottles and corks to contain it.

A legal loophole uniquely allows Americans to call their sparkling wines champagne. The Treaty of Madrid decreed that only the Champagne region may use that name. This was reaffirmed by the Treaty of Versailles but the US signed a separate peace agreement with Germany. When prohibition was lifted, American wine-⁠merchants took advantage of this loophole, freely selling their own Champagne, much to the annoyance of the French.

Only seven prisoners were freed by the storming of the Bastille. In France, 14 July, Bastille Day, is a national holiday and a glorious national symbol. From the rousing paintings of the scene, you might think hundreds of proud revolutionaries flooded into the streets waving tricolours. In fact, only just over half a dozen people were being held at the time of the siege.

One hundred lives were lost in the attack, including that of the governor, whose head was carried through Paris on a pike. Soldiers invalided out of regular service  — and conditions were fairly comfortable for most inmates, with relaxed visiting hours and furnished lodgings. The painter Jean Fragonard’s sketch of visiting day in 1785 shows fashionable ladies promenading around the courtyard with the prisoners, who were given a generous spending allowance, plenty of tobacco and alcohol, and were allowed to keep pets.

St. Bernards have never carried brandy barrels. The dog’s mission is entirely different  — apart from anything else giving brandy to someone with hypothermia is a disastrous mistake  — but tourists have always loved the idea, so they still pose wearing them. Before they were trained as mountain rescue dogs, they were used by the monks at the hospice to carry food, as their large size and docile temperament made them good pack animals.

The brandy barrel was the idea of a young English, who was much favoured by Queen Victoria. He was a renowned painter of landscapes and animals, best known for his painting The Monarch of the Glen and for sculpting the lions around the base of Nelson’s Column. Originally, St Bernards were known as Barry hounds, who rescued forty people but was unfortunately killed by the forty-⁠first, who mistook him for a wolf.

Charles Darwin was driven by gastronomic, as well as scientific, curiosity and once ate an oil. While reading Divinity at Cambridge University, he became a member of the Glutton club which met once a week and actively sought to eat animals not normally found on menus. Darwin’s son commenting on his father’s letters, noted that the Glutton club enjoyed, among other things, hawk and bittern.

Over the years, Darwin sharpened up considerably in the academic arena and lost his faith in God, but he never lost his taste for the allure of an interesting menu. In the Galapagos, Darwin wolfed down a few helpings of giant tortoise. Not realising the importance of giant tortoises to his later evolutionary theory, forty-⁠eight specimens were loaded aboard the Beagle. Darwin and his shipmates proceeded to eat them, throwing the shells overboard as they finished.

Nelson never wore an eye-⁠patch. He didn’t wear anything at all over his damaged right eye. Though he had an eye-⁠shade built into his hat to protect his good left eye from the sun. Nelson didn’t have a blind eye. His right one was badly damaged at the siege in 1794. A French cannon ball threw sand and debris into it, but it still looked normal  — so normal, in fact, he had difficulty convincing the Royal Navy he was eligible for a disability pension.

There is no contemporary portrait of Nelson wearing an eye-⁠patch, and despite what most people recall having seen, the prominent column shows him without an eye-⁠patch. It was only after his death that the eye-⁠patch was used to add pathos to portraits. He used the damaged eye to his advantage. At the battle of Copenhagen, he ignored the recall signal issued by his superior.

As well as mercury, gallium and francium can all be liquids at room temperature. Gallium was discovered by French chemist in 1875. It was the first new element to confirm Dmitri Mendeleev’s prediction of the periodic table. Gallium is used chiefly in microchips because of its strange electronic properties. Compact disc players also make use of it because when mixed with arsenic it transforms an electric current directly into laser light.

Francium is one of the rarest elements. It has been calculated there are only ever thirty grams of it present on Earth. This is because it is so radioactive it quickly decays into other, more stable elements. So it is a liquid metal, but not for very long  — a few seconds at most. It was the last element to be found in nature. These elements are liquid at unusually low temperatures for metals because the arrangement of electrons in their atoms makes it hard for them to get close enough to each other.

Silver is the best conductor. The best conductor of both heat and electricity is also the most reflective of all the elements. Its drawback is that it is expensive. The reason we use copper wire in our electrical equipment is because copper  — the second most conductive element  — is much cheaper. As well as its decorative uses, silver is now mostly used in the photographic industry.

Silver has the curious property of sterilising water. Only tiny amounts are needed  — just ten parts per billion. Both the Romans and Greeks noticed that food and drink put in silver containers did not spoil so quickly. Silver’s strong antibacterial qualities were made use of for many centuries before bacteria were discovered. This may also explain why silver coins are often found at the bottom of ancient wells. While silver will certainly kill bacteria in the lab, whether or not it will do so in the body is controversial. Many of the supposed advantages are unproven.

All diamonds are formed under immense heat and pressure beneath the earth and are brought to the surface in volcanic eruptions. They are formed between 100 miles underground. Most are found inside a volcanic rock and mined in areas where volcanic activity is still common. Any other diamonds are found loose.

Twenty countries in the world produce diamonds. South Africa is now the fifth largest. Diamonds are made of pure carbon. So is graphite, the stuff that the lead in pencils is made from, but with the carbon atoms arranged differently. Diamond is one of the hardest naturally occurring substances on earth, but graphite is one of the softest with a score of one and a half. The largest known diamond is 2,500 miles across and measures ten billion trillion trillion carats. Found directly above Australia the diamond sits inside the star Lucy.

What does the Moon smell like? Like gunpowder, apparently. Only twelve people have walked on the moon, all of them American. Obviously, in their airtight space suits the astronauts could not actually smell the Moon, but moondust is clingy stuff, and plenty of it was traipsed back into the cabin when they returned from the Moon’s surface. They reported that moondust feels like snow, smells like gunpowder, and doesn’t taste too bad.

Moon’s surface. It also contains minerals like iron, calcium and magnesium. NASA employs a small team to sniff every single piece of equipment which goes onto its space flights. This is to ensure that no items which could change the delicate balance of the climate of the International Space Station make it on to shuttles. The idea that the Moon was made of cheese seems to date from the sixteenth century. The first citation from John Heywood says that the moon is made of green cheese.

How many planets are there in the solar system? Eight. If you still think there’s nine you’ve obviously been living in a parallel solar system. Planets must fulfil three criteria: they have to orbit the sun, have enough mass to be spherical, and to have cleared the neighbourhood around their orbit. Pluto only managed the first two, so was demoted to the status of dwarf planet.

It’s not perfect. Some astronomers argue that neither Earth, Jupiter or Neptune have cleared their orbits either. But it does resolve the mysterious position of Pluto. Even the planet’s discoverers weren’t fully convinced of its status. Pluto is much smaller than all the other planets, a fifth the mass of the Moon and smaller than seven of the moons of other planets. It isn’t much larger than its own main moon. Its orbit is eccentric and on a different plane from the other planets, and its composition is completely different.

Atom consists of mostly nothing. The vast majority of an atom is empty space. To get it into perspective, imagine an atom the size of an international sports stadium. The electrons are right up at the top of the stands, each smaller than a pin-⁠head. The nucleus of the atom is on the centre spot of the pitch, and is about the size of a pea. For many centuries, atoms, which were entirely theoretical, were thought to be the smallest possible units of matter, hence the word, which means not-⁠cut in Greek.

Then the electron was discovered. The atom was split and the neutron discovered in 1932. This was by no means the end of the matter. These even tinier units called quarks are given names like strangeness and charm and come not in different shapes and sizes but flavours. Whatever matter might be, no one seemed able to get to the bottom of it.

Nitrogen is main ingredient of air. As every twelve-⁠year-⁠old knows, it accounts for 78 percent of the air. Less than 21 percent of air is oxygen. The high percentage of nitrogen in the air is a result of volcanic eruptions during the formation of the Earth. Vast amounts of it were released into the atmosphere. Being heavier than hydrogen or helium it has stayed closer to the surface of the planet. A key ingredient in gunpowder, it is also used to cure meat, as a preservative in ice cream.

The word nitrogen means soda-⁠forming in Greek. Beer cans with pressure-⁠sensitive widgets contain nitrogen, not carbon dioxide. The smaller nitrogen bubbles make a smoother, creamier head. The only other significant gas in air is argon. It was discovered by William John Strutt, who was also the first man to work out why the sky is blue.

The hippopotamuses are most dangerous for humans. Unfortunately hippos like to hang out near slow-⁠moving fresh water. Most accidents occur because people are out walking at night, just the time when hippos leave the water to graze. Being trampled by a startled hippo is not a dignified way to die. Hippopotamuses, once believed to be members of the pig family but now shown to be most closely related to whales, are divided into two species. The common hippo is the third largest land mammal after the African and Asian elephants.

They are very irritable beasts, especially when they have young. They dispose of lions by plunging them into deep water and drowning them, crocodiles by biting them in half, and sharks by dragging them out of the water and trampling them to death. However, they are strict vegetarians, so their aggression is mostly to do with self-⁠defence. Hippos mainly eat grass.

Nicotine is colourless. In theory, cigarettes can be made out of potato or tomato leaves. Some programmes designed to help people stop smoking also advise giving up potatoes and tomatoes in order to eliminate low-⁠level nicotine intake completely. In small doses, the nicotine compound that is present in all these plants produces feelings of pleasure. That’s why tobacco is more addictive than either cocaine or heroin. But it’s also why we sometimes find ourselves craving chips or pizza.

In large doses, however, nicotine is as deadly as the nightshade whose relative it is. The nicotine in a single cigarette, if taken direct into the bloodstream, would be fatal. Eating one cigarette could make you severely ill. Swallowing a packet of ten would definitely kill you. In 1976, the Department of Health urged pregnant mothers to wear rubber gloves when peeling potatoes. More than a kilogram of potatoes eaten at a single sitting would be certain death.

For crocodiles an ordinary rubber band should be sufficient for you to make your escape. The muscles that close the jaws of a crocodile or alligator are strong. They have the same downward force of a truck falling off a cliff. But the muscles that open their jaws are weak enough for you to hold their mouths shut with one hand. The technical difference between alligators and crocodiles is that crocs have a longer, narrower snout, eyes further forward.

Also, some crocodiles live in salty water. Alligators generally live in fresh water. Crocodile means lizard. Neither animal cries as it savages you to death. Crocodile tears are a myth from medieval times. The origin of the legend may be in the proximity of the throat to the glands which lubricate the eye. These can cause the eye to water a little from the effort of swallowing something large or reluctant. They can’t smile either: crocodiles and alligators have no lips.

Work is a bigger killer than drink, drugs or war. Around two million people die every year from work-⁠related accidents and diseases. Worldwide, the most dangerous jobs are in agriculture, mining and construction. The second most dangerous job was fishing and third was airplane pilots. Nearly all of the pilots died in small-⁠plane crashes, not passenger jets. The third most common cause of death on the job in all occupations was murder. Fifty policemen were murdered. Falls were the second most common cause of death.

Roofers and structural-⁠metalworkers were the main victims. The most common cause of death on the job was the car accident. Even police officers were slightly more likely to die behind the wheel than by homicide. The risk of death can be calculated using the Duckworth scale. It measures the likelihood of dying as a result of any given activity. The safest kind of activity scores zero and eight will result in certain death.

Neither Roman spectators calling for the death of a gladiator, nor Roman Emperors authorizing one, ever gave a thumbs down. In fact, the Romans didn’t use a thumbs down sign at all. If death was desired, the thumb was stuck up  — like a drawn sword. For a loser’s life to be spared, the thumb was tucked away inside the closed fist  — as with a sheathed weapon. If further proof were needed, in 1997 a Roman medallion of the second or third century AD was discovered in southern France. It shows two gladiators at the end of a battle and a referee pressing his thumb against a closed fist. The inscription reads: Those standing should be released.

This has been problematic in Iraq, where American soldiers are unsure whether locals are welcoming them or about to blow them up. Desmond Morris traces the positive connotations of the thumbs up in Britain to the Middle Ages, where it was used to close business deals. It found a new lease of life in World War Two when US airforce pilots adopted it as a signal to ground crews before take-⁠off.

The oldest definite record of someone using a V-⁠sign only dates back as far as 1901, when there is documentary footage of a young man who clearly didn’t want to be filmed using the gesture to camera outside an ironworks. This proves that the gesture was being used by the late nineteenth century. According to the legend, English archers waved their fingers in contempt at their French counterparts, who were supposed to be in the habit of cutting off the fingers of captured bowmen  — a fingerless archer being useless, as he could not draw back the string.

But if archers were captured by the French they were much more likely to be killed rather than be subject to the time-⁠consuming process of having their fingers amputated. Prisoners were usually only taken to be ransomed and bowmen were considered inferior merchandise. Whatever its date of origin, the V-⁠sign wasn’t universally understood until quite recently when Winston Churchill first began to use it.

The usual answer that water doesn’t have any colour. It’s clear or transparent and the sea only appears blue because of the reflection of the sky. But in fact water really is blue. It’s an incredibly faint shade, but it is blue. You can see this in nature when you look into a deep hole in the snow, or through the thick ice of a frozen waterfall. If you took a very large, very deep white pool, filled it with water and looked straight down through it, the water would be blue.

This faint blue tinge doesn’t explain why water sometimes takes on a strikingly blue appearance when we look at it rather than through it. Reflected colour from the sky obviously plays an important part. But not all the light we see is reflected from the surface of the water. Some of it is coming from under the surface. The more impure the water, the more colour it will reflect.

Camels don’t store water, but fat, which is used as an energy reserve. Water is stored throughout their bodies, particularly in the bloodstream, which makes them very good at avoiding dehydration. Camels can lose 40 per cent of their body-⁠weight before they are affected by it. When they do drink, they really go for it  — up to 225 litres at a time. Here are a few quite interesting facts about camels, which have nothing to do with their humps. Before elephants acquired their reputation for long memories, the ancient Greeks believed it was camels that didn’t forget.

Camel-⁠racing in the United Arab Emirates has started to use robot riders in place of the traditional child jockeys. The remotely operated riders were developed following a ban on the use of jockeys under sixteen years of age. The only qualifications needed to become a jockey are not to weigh much and be able to scream in terror.

Spencer was an engineer, philosopher and psychologist, who in his day was as famous as Darwin. He first coined the phrase ‘survival of the fittest’. Darwin paid him the compliment of using it himself. Herbert was the eldest of nine children, all the rest of whom died in infancy. Trained as a civil engineer, he became a philosopher, psychologist, sociologist, economist and inventor. He sold more than a million books in his lifetime and was the first to apply evolutionary theory to psychology, philosophy and the study of society.

He also invented the paperclip. The device was called Spencer’s Binding Pin and was produced on a modified hook-⁠and-⁠eye machine. It did well in its first year, but demand dried up. During the Second World War, paperclips were an emotive symbol of Norwegian resistance to the German occupation. A giant paperclip was later erected in Oslo.

Cobras in snake-⁠charming acts are responding to the sight of the flute, not its sound. Snakes don’t really hear music though they are certainly not deaf. They have no external ears or eardrums, but can sense vibrations transmitted up from the ground into their jaw and the belly muscles. They also seem to be able to detect airborne sounds via an inner ear. It used to be thought that snakes could not hear at all because they don’t respond to loud noises but research at Princeton has shown that they have acute hearing.

The key discovery was how the snake’s inner ear functions. It appears that their hearing is tuned to the frequency range of noises and vibrations made by the movement of larger animals, so music would be meaningless to them. Charmed cobras stand upright if threatened and sway in response to the movement of the instrument. If they strike at the flute, they hurt themselves, so they don’t do it again.

No ostrich has ever been observed to bury its head in the sand. It would suffocate if it did. When danger threatens, ostriches run away like any other sensible animal. The myth about ostriches may have arisen because they sometimes lie down in their nest with their necks stretched out flat and scan the horizon for trouble. If the predator gets too close they get up and leg it. The ostrich is the largest bird in the world.

The head-⁠burying myth was first reported by the Roman historian, who also thought ostriches could hatch their eggs by looking at them aggressively. He didn’t mention their ability to swallow odd things. As well as the stones they use to aid digestion, ostriches will eat iron, copper, brick or glass. One ostrich in London Zoo was found to have eaten a metre-⁠length of rope, a spool of film, a watch and a number of coins.

There is an established stereotype among foreigners that Russia is a country of eternal frost and snow-⁠covered streets. This is all because for many years foreigners have been frightened by the phrase "Russian winter". But it's not all that simple, Russia is a vast country and the weather in different areas can be completely different. Russia consists of several continental zones. For example, in the north winters are long and harsh, in some places there is lots of snow and temperatures fall below −40 degrees Celsius. These winters are normal, not only in the northern regions of the country but even in the Far East. Summers in these areas don't even see three warm months out of the year.

The closer you get to the south the warmer the Russian climate gets. In the central part of the country summer becomes warm  — even hot  — which makes it possible for a good harvest of grain, fruit and vegetables. Winters here are not extremely cold and the average winter temperature does not fall below −15 degrees Celsius. By the way, in Russia the real warmth does not start until the middle of April. And only at the end of May does everything start to bloom and people go without their warm clothing.

The mystery of why trees don’t stop growing is still unsolved. Human beings usually stop growing sometime during their teens. Many animals reach full growth within a year. Others are fully grown in just a few years. Birds and insects also stop growing at a certain age. But trees keep growing as long as they live. Trees live, grow, and reproduce themselves by an amazing process. The thousands of leaves put forth by the tree breathe for it and manufacture its food. Its root system gathers minerals and vast quantities of water. To carry this water to the leaves, the tree is equipped with an intricate circulation system that extends upward from the millions of root hairs through the trunk and branches. The trunk holds the leaves up to the sunlight, sends them water from the roots, and gets food back from them. Then seeds are borne in flowers or cones.

Many parents do not like their children to play video games. One reason is that it is a waste of time. Instead of playing games, they could be spending their time wisely, doing homework, exercising, or cleaning the house. Another reason is that many games are destructive and violent, causing children to behave badly and aggressively in the real world. Finally, video games are often addictive and thus discourage children from having other hobbies and interests. All of these are good reasons to dislike video games. Nevertheless, there are some good reasons to allow children to play them. For one thing, not all video games are mindless time-⁠wasters. Nowadays, there is much more variety and lots of games to choose from that are educational and instructive. Parents simply need to spend more time paying attention to the kinds of games children play and encourage them to choose games that develop their minds.

Because birds have such fine eyesight, they are hard to approach. Bird watchers use binoculars to study birds. One way to watch them up close without using binoculars is to go to a place they go to often. Sit still, keep quiet, and wait until they come. Soon they will be doing things all around you.

You may get too close to the animals you are watching. Always stay at a distance that is easy for them and for you. Do not disturb nesting birds. And never approach an animal that is with its young. Wild animal parents can be very protective. If you come upon a baby animal that looks like it’s alone, let it be. Mother may be watching you from a hiding place nearby.

Do not touch or corner a wild animal. Never follow an animal into places you don’t know. There is no such thing as a tame wild animal.

Some paintings found in different caves around the world are recognized as the work of Stone Age artists. But what was the purpose of the paintings? Why were they hidden in a dark room where there is no evidence that cave people lived?

No one really knows, but there is one theory that makes great sense. It is called the theory of Sympathetic Magic. According to this, the cave people believed that if they could make a likeness of an animal, they could put a spell over it. This spell would give the tribe power over the live animal.

Stone Age existence depended on killing animals  — for food, clothing, and even weapons and tools. The animals were large and fierce; the cave people had only the most simple weapons. Hunters had to be brave and fearless. They needed more than a spear or club; they needed all the magic they could get. The magic could help the hunters catch the animals.

Celebrating New Year’s is a universal tradition, but countries see the New Year in with different customs. You are probably familiar with the New Year’s Eve traditions of your own country, but do you know what the holiday looks like elsewhere around the globe? While many countries have fireworks, some also have their own unique traditions and customs. Here's a taste of some of the ways different countries usher in the New Year. Spanish New Year’s Eve usually starts with a traditional family dinner, but perhaps the most notable tradition is the countdown to midnight. Just before the clock strikes midnight, 12 grapes should be eaten as quickly as possible. In Russia a popular tradition is to bid farewell to the last year and welcome in the new one. Shortly before midnight, many Russians tune in to watch the president’s speech on TV or watch popular New Year shows.

The first maps were drawn by explorers to help them find their way home and show people where they had been. The maps showed the shape of the land, distances between places and special features such as caves and old trees. Nowadays, maps show the towns and villages, and the roads, railways, rivers and mountains. Symbols are used to show all the different things on a map and there is a key to explain what the symbols stand for.

Over the centuries, people explored most of the Earth and put together the map of the world we use today. Maps of the world or large areas are often either "political" or "physical". The political map shows territorial borders. The purpose of the physical map is to show features of geography such as mountains, soil type or land use including roads, railroads and buildings.

Islands that appear and disappear are certainly part of the world's legends. But in 1963, with the aid of cameras and scientific observers, some of those legends were given a solid basis of fact. For example, on November 13, 1963, a kind of miracle occured. An island was born.

On that day a fishing boat sailed into waters that were boiling and rolling and foul with a strong smell. The world still had a hard time believing the miracle that was to occur. It was the first time that scientists were to witness the unexpected birth of an underwater island.

First the engineer, then the captain, and at last the cook were aware of awful smell and the peculiar roll of the sea. But it was the cook who first noticed the smoke. He thought there was a ship in trouble somewhere on the seas.

Until fairly recently, it was a mystery how certain large bees, bumblebees in particular, were able to fly. To scientists who study the physical laws of flight a bee’s body seemed too heavy and its wings too small for it to become airborne and remain so. Bees "can’t" fly... but do. The mystery became so intriguing that a few scientists decided to study it.

Most insects fly by using muscles that flap their wings with great speed. For example, the locust beats its wings at a rate of about 20 times per second to fly. Other flying insects have to beat their wings even faster  — some as rapidly as 100 times per second.

But bees must work extra hard to become airborne. Honeybees, for instance, must beat their wings about 200 times a second to fly. Yet larger bees  — like bumblebees  — whose bodies are heavier, wider, and longer  — have to do even better.

There are hobbies of different kinds. Some are indoor activities and the others are outdoor activities. Some help in relaxing the mind and some the body and some others both mind and body. Collecting stamps, coins, pictures and the like, listening to music, and reading a book can be called indoor hobbies. Drawing, painting, photography, writing poetry and the like may be called both indoor and outdoor hobbies. Gardening, hunting, fishing, swimming, bird watching, and star gazing are all outdoor hobbies.

People choose their hobbies according to their interests and tastes. Relaxation and pleasure are the principles that guide the choice. Hobbies not only delight, but also educate. Hobbies develop curiosity. Collecting stamps and coins of various countries, no doubt, gives pleasure. At the same time, it helps one to know the geography, the history and the culture of the countries concerned.

Yasnaya Polyana is the country estate where the great Russian writer Leo Tolstoy lived, wrote and spent most of his long life. He was born here in 1828 and he was buried here in 1910. It was in Yasnaya Polyana that Tolstoy wrote many of his great novels. Many of Tolstoy's famous contemporaries visited him in Yasnaya Polyana. Writers, composers, painters, political leaders  — eminent figures from the arts, social thought, politics and also workers, peasants and students came to see him.

Life on the estate and the beauty of the countryside are reflected in many of his writings. Constant contact with the local peasants was a source of Tolstoy's knowledge of the life of common people. His own life as a thinker and a writer inspires people all over the world with a desire for truth, goodness and justice. In his writings, Leo Tolstoy gave the world a unique picture of Russian life.

A mountain is a form of land that rises high in a limited area. It is higher and steeper than a hill. Mountains must be higher than 600 metres. They consist of rocks and earth. They usually have steep, sloping sides. They also have sharp or slightly rounded peaks. Some mountains may have trees which grow on their sides. Very high mountains may have snow on their peaks. Long chains or groups of mountains are mountain ranges. They can be short or very long. A group of these makes a mountain system.

Mountains exist on every continent of our planet and even beneath the ocean. In fact, some of the highest mountains are at the bottom of the sea. For example, Hawaii is at the top of a volcanic mountain in the Pacific Ocean. More than half the mountain is below water. 75% of the world’s countries have mountains.

When you hear the word "panda", Kung Fu Panda is the first thing that comes to your mind. Pandas are an extremely popular animal. They look nice. Even small children recognize a panda when they see it. Still, most present-⁠day toddlers know about pandas from movies and not books. Pandas are also called "panda bears". The general life span of a panda is 20 years if they are wild. It can be up to 25 years if they are captive and protected. There is an interesting thing about the eye patch of the panda. When a panda is a cub, it is circular in shape. Along its life journey it changes to the shape of a teardrop. Pandas are only found in China. For quite a while now, Chinese people have used panda as a symbol of peace. In ancient times, a white flag with a picture of panda was raised in order to declare peace during wars.

Many of our superstitions came to us from very ancient sources. The idea that one should knock on wood for good luck, for example, is a 4,000-⁠year-⁠old custom that began with some Native American tribes of North America. Noticing that the oak was struck often by lightning, members of the tribe thought that it must be the dwelling place of a sky god. They also thought that boasting of a future personal deed was bad luck and meant the thing would never happen. Knocking on an oak tree was a way of contacting the sky god and being forgiven for boasting.

Another interesting superstition is that it is bad luck to open an umbrella indoors. In eighteenth-⁠century England, umbrellas had stiff springs and very strong metal spokes. Opening one indoors could indeed cause an accident. It could injure someone or break a fragile object. This superstition came about for practical reasons.

Earthquakes are one of the most powerful events on the earth. When large sections of underground rock break and move suddenly, and earthquake occurs. This causes the ground to shake back and forth. Small earthquakes do not cause much damage, but large ones do. Some earthquakes have caused buildings and bridges to fall. Others have caused rivers to change their paths. Earthquakes near mountains and cliffs can cause landslides that cover up the houses and roads below. A large earthquake under the ocean can cause giant waves that flood the seashore. When large earthquakes occur in a city, there is danger of fire from broken gas and electric lines. Damaged roads make it difficult for rescue workers to help people. Scientists are trying to find ways to predict when an earthquake will happen so that people can be warned ahead of time.

The idea of storing food in tin cans was developed in England in the early 19th century. A British merchant named Peter Durand is responsible for this idea. The main market for canned food at that time was the British Army and Royal Navy, but it is known, that Queen Charlotte, wife of King George III, first tried and enjoyed canned beef in 1813. It is interesting that no one invented a can opener until fifty years later. For a long time, British soldiers tore open canned food with pocket knives. They were even known to shoot the cans open. The can opener that we use today was invented about 1870. It had a cutting wheel that rotated around the can’s edge. It was immediately popular and it has been changed only once. In another 55 years, a special wheel was added. This was called the "feed wheel" and it made the can rotate against the cutting wheel.

Birds live everywhere. They vary from pigeons in big cities to penguins in the Antarctic. However, all birds have similar features. For example, they all have wings. Still, not all of them can fly. All birds also have feathers. In fact, birds are the only living animals that have feathers. Birds build nests, in which female birds lay eggs.

Birds are warm-⁠blooded. It means that their body temperature stays about the same. It doesn’t depend much on the temperature of their surroundings. Mammals, including humans, are also warm-⁠blooded.

Birds have always fascinated people. Many people keep birds as pets. We also enjoy watching them in the wild or at zoos. In addition, farmers raise chickens, ducks and geese for their meat and eggs. Also, some people are quite fond of bird hunting.

Windsurfers use a sailboard. It is a board much like a surfboard. It is made of plastic or fiberglass. A mast, or vertical pole, stands in the center of the board. The sail is hooked to the mast. There is a plastic window in the sail, so that the surfer can see where the board is going. The surfer keeps his or her balance and steers by holding onto a boom. The boom is a horizontal bar that is attached to the sail. The surfer lifts the sail out of the water with a rope that is attached to the boom. There have been many arguments over who first invented the sailboard. In 1982, a court ruled out that a 12-⁠year-⁠old British boy had made the first sailboard in 1958. This sport first became popular in Europe in the 1970s. Funboarding is a special kind of windsurfing. Funboards were designed to be used in strong winds. It is a popular sport in Hawaii.

Brushing teeth is a good habit which is common to people all over the world. This habit has been developing since 3000 B.C., when people used twigs for brushing their teeth. Modern toothbrushing dates back to 1770, when a modern tooth brush was invented by William Addis. William Addis lived in England and was in prison for causing a riot when he made his invention. He was watching a guard sweep the floor with a broom and wondered if the same principle could be used for brushing teeth. He kept a small lamb bone from his lunch, drilled some holes in it and pulled some pig bristles through them. When William Addis was released, he started a toothbrush business and became rich. After his death, his business remained in his family for almost 200 years. The company still exists in the UK and produces 70 million toothbrushes per year!

A fork is a common tool used in eating in many countries around the world. It usually has three or four stiff metal points that are attached to a handle. Although bigger forks made of bone, bronze or even silver were used in cooking as early as 4,000 years ago, the personal table fork was probably invented around the 4th century AD in the Middle East. The first European country to adopt the fork was Italy where it became really popular among rich people around the 14th century and by the 16th century had become more or less common. From Italy the new fashion of eating spread into Spain and France. Northern Europe was not so fast to accept a new tool. People considered it ‘unmanly’ and ‘too delicate’. It was only in the 18th century that the fork became popular in Great Britain. As for North America, the fork made its way there around the time of the American Revolution.

More than 200 years ago, English explorers arrived on the shore of Australia. They were surprised to see large animals hopping about as if on springs! Today, kangaroos continue to amaze us. There are more than 50 different kinds of kangaroos that can be of different sizes from tiny to tall. The rat-⁠kangaroo is the smallest and weighs only about 500 grams. The largest, the red kangaroo, can stand as tall as a man and weigh 100 kg. Kangaroos move by hopping. They have very large back legs and feet. These legs are very strong and muscular. They also have large strong tails. Thanks to the muscles, kangaroos can hop with enormous power. The large kangaroos can cover more than 60 meters with each hop. They can move easily at the speed of 30 km per hour. And they can reach a top speed of over 80 km per hour.