Lis le monde en anglais.

Why traffic lights were invented before cars

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Traffic light

The first traffic light arrived in 1868. London put it up outside Parliament. It burned gas and showed red and green. A police officer turned it by hand. It stopped horses and carts, not cars. The first car came eighteen years later! Sadly, the lantern exploded after a few weeks.

How the can opener came decades after canned food

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Can opener

Food in cans started in 1810. People hammered and chiseled cans open. The can opener appeared only in 1855. For forty-five years, people struggled with hard metal cans. Finally, someone invented a tool to open them easily. Before that, a knife was your only friend!

How your body produces vitamin D from sunlight

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Vitamin D

Sunlight touches your skin and something amazing happens. Your body creates vitamin D. This vitamin is very important for your bones and teeth. You need only ten to thirty minutes of sun. Dark skin needs more time than light skin. Your body is like a tiny vitamin factory!

Why some people are naturally left-handed

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Left-handedness

About ten per cent of people are left-handed. Scientists do not know exactly why. Genes play a role, but it is not simple. Left-handed people use their left hand naturally and easily. The right side of their brain controls the left side. Left-handedness is normal and special!

Why pretzels are twisted into their classic shape

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Pretzel

Pretzels come from Austria and Germany. Long ago, monks twisted dough into a special shape. The twist looks like crossed arms. Pretzels were a reward for children who learned prayers. Today we eat them for fun. The twist shape is still famous worldwide!

How sourdough bread uses wild yeast

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Sourdough

Sourdough is very old bread. It does not use commercial yeast. Wild yeast lives in flour and the air. Bacteria and yeast grow together in the dough. This makes the bread sour and tangy. Sourdough is slow bread. It takes time to rise, but it tastes wonderful!

The world's oldest known song is over three thousand years old

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Hurrian Hymn

The oldest song ever found is from ancient Ugarit. It is over three thousand years old. People carved the song on a clay tablet. The song had lyrics and music notation. We can still play it today on modern instruments. This ancient music still speaks to us!

How orchestras tune before every performance

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Orchestra

Before a concert, orchestras tune carefully. All instruments must match the same note. The oboe gives the note. Its sound cuts through everything else. The other players listen and adjust. On stage this takes less than a minute! Perfect tuning makes the orchestra sound beautiful.

Why elephants cannot jump

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Elephant

Elephants are very large and very heavy. They cannot jump at all. Their legs are too heavy for jumping. Elephants walk slowly and carefully instead. Few animals share this trait with them. But elephants can run and swim very well!

Why some birds mimic human speech

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Parrot

Parrots and other birds copy human words. They do not understand the words. Birds copy sounds because they are social animals. In the wild, birds copy each other's calls. A parrot in a house hears human voices and copies them. It is natural behaviour!

How ancient Egyptians used blue pigment first

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Egyptian blue

Ancient Egypt created blue pigment first. They mixed copper minerals with sand and heat. This blue was special and expensive. Only kings and gods wore blue. Other cultures learned from Egypt later. Blue became the colour of power and heaven!

How ancient frescoes were painted onto wet plaster

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Fresco

Frescoes are paintings on wet plaster walls. Artists painted quickly before plaster dried. The paint soaked into the plaster permanently. Ancient Rome and Renaissance Italy loved frescoes. This technique made pictures last for centuries. Michelangelo painted famous frescoes in the Sistine Chapel!

European women plucked their eyebrows, then glued new ones on

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Medieval fashion

In the late Middle Ages, a high forehead was beautiful. Women plucked their eyebrows away completely. Fake eyebrows came much later. In Britain, in the 1700s, women glued new ones on. They cut them from mouse fur! Many faces had scars from smallpox. So thin eyebrows were common. Today we think it looks strange!

Ancient Romans used urine to whiten their teeth

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Ancient Rome

Romans wanted white teeth. Old urine turns into ammonia. Ammonia really does clean and bleach. Pots stood at street corners for passers-by. Cloth workers collected them to wash wool. Rome even taxed this strange trade! The emperor Vespasian said money never smells. Ammonia stayed in toothpaste until the 1900s.

Marie Antoinette never actually said that famous cake line

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Marie Antoinette

Marie Antoinette is famous for one line. People say she said: 'Let them eat cake.' She never said it. The writer Rousseau told this story first. He wrote it around 1766. Marie Antoinette was ten years old then! She still lived in Vienna. People gave her the line much later.

How astronauts' blood behaves differently in space

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Astronaut

In space, gravity does not pull blood down. Blood distributes differently in the body. Astronauts' faces swell slightly from fluid. Their legs become very thin. The heart pumps less hard. This happens quickly in space. When astronauts return home, their bodies adjust again!

Why the far side of the moon looks different

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Far side of the moon

The Moon always shows the same side to Earth. For a long time nobody saw the far side. Then a Soviet probe flew around it. It took photos in October 1959. The far side was a surprise. It has almost no dark plains. Its crust is thicker there. So the lava never reached the surface.

Why footprints on Mars do not last

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Mars

Footprints on the Moon last for millions of years. Nothing up there moves the dust. Mars is different! The air is thin, but it blows. Dust devils cross the plains all the time. Cameras in orbit watch the rover tracks. The tracks fade away in a few years. A boot print disappears the same way.