The Wonderful World of Science: Class 6 Science · Chapter 1

Born curious

Watch a baby for a few minutes. She grabs a spoon and bangs it on the floor. Then she puts it in her mouth. She drops it again and again, just to see what happens. Nobody taught her to do this. Babies are explorers from the very first day.

You were one of those explorers too. Maybe you poked at ants with a twig. Maybe you stamped on dry leaves to hear them crunch, or pulled a toy apart to see what was inside. Every “why?” you asked was the start of an investigation.

In the Middle Stage, all that poking and wondering gets a name of its own: science (विज्ञान). This book is called Curiosity, and for a good reason. Curiosity (जिज्ञासा), the itch to find out more, is the fuel that keeps science going.

Look at Fig. 1.1. Not one of those questions came from a textbook. They came from one ordinary day. Science begins exactly like this: you notice something, and you wonder about it.

What is science?

So what exactly is science? Science is how we find things out. We look closely, ask questions, try ideas out and think hard about what happened. Facts are the treasure that science digs up, but the digging itself is the science.

In some ways, a scientist is like a detective. A detective gathers clues, thinks of possible suspects and checks each one. A scientist gathers observations, thinks of possible answers and tests each one. Only the mysteries are different. Why does an iron gate rust? Why does chopping onions make our eyes water? What makes a firefly glow in the dark? All you need to join the hunt is curiosity.

Science is everywhere

Science is interested in things of every size. A single drop of pond water can hold hundreds of living things too small to see. An ant finds its way home across a busy floor. A banyan tree lets roots dangle from its branches. A volcano spits out melted rock. The Sun is so big that more than a million Earths could fit inside it. Every one of them hides questions (Fig. 1.2).

You do not have to travel anywhere to find science. It is in the bathroom mirror that fogs up after a warm bath. It is in the way you lurch forward when a bus brakes hard. It is in the mehndi that leaves an orange pattern on your palm. It is even in a spinning top, a लट्टू, that stays upright only while it spins.

Great discoveries do not always start in a laboratory. Sometimes they start with a traveller gazing at the view.

Knowledge keeps growing

Every time we answer one question, something funny happens: the answer brings new questions with it! Picture everything we know as an island in a huge sea of things nobody knows yet (Fig. 1.3). Each discovery makes the island bigger. But a bigger island has a longer shore, and the shore is where fresh questions wash up.

For a long time, many people believed that the Sun travelled around the Earth. Careful watching of the sky showed the opposite: the Earth goes around the Sun. That part of the map of knowledge had to be redrawn. Changing our minds when new evidence (प्रमाण) arrives is not a weakness. It is how science gets better.

Another surprise lies ahead: the topics in science are not separate boxes. The Sun's heat dries up puddles. That water rises into the air and forms clouds. Clouds bring rain, and rain helps grow the crops that end up on your plate. Pull one thread and many others move.

What will we explore in this book?

This book is a journey. Before we set off, let us look at the map (Fig. 1.4).

Our first stop is life itself. A tadpole in a monsoon puddle sprouts legs, loses its tail and hops off as a frog. A fluffy chick becomes a hen in a few months. Even your own hair and nails keep growing all through your life. Living things also come in a dazzling variety. Camels cope with scorching deserts, snow leopards with icy mountains and fish with salty seas. How does each one survive in its home? And what does any living thing need before it can grow?

Now zoom far out, as if you were looking back from space. People have studied many planets and moons, and so far they have found living things on just one of them: the Earth. That makes our planet a rare and precious home, and caring for it is a job for all of us.

The next stop is food. Think about your last meal. Which parts came from plants, and which from animals? Why do we need a mix of foods to stay healthy? Is a plate of pakodas as good for us as a bowl of sprouts? And why does a meal of dal-baati in Rajasthan look so different from appam and stew in Kerala? Later, a few drops of iodine will even help you spot starch hiding in your food.

The third stop is stuff: what everything around us is made of. Why are cooking pots made of metal, but their handles often of wood or plastic? Why are raincoats not made of cotton? When wheat is cleaned in the wind, why does the light husk fly away while the grain drops down? Why does a magnet cling to the fridge door but not to a wooden door? And how can we measure how long a corridor is, or describe the way a swing moves?

Water gets a whole chapter of its own. Why do wet clothes dry on a line? Where do the dewdrops on winter grass come from? How does a clay matka keep its water so cold? We will also learn to measure how hot or cold things are. Why is a doctor's thermometer different from the one used in a laboratory?

The last stop is high above our heads. Which planets can you spot without a telescope? How can a group of stars help you find north? On the way we will also meet nature's treasures, such as air, water and forests, which all of us share. At every stop you will build, test and measure things for yourself.

Finding answers on our own

It was Makar Sankranti, and the sky above Kabir's terrace was full of kites. Kabir's new kite, though, refused to behave. Each time it climbed, it tipped over and dived to the left. His little sister laughed. Kabir frowned and started to think.

“It must be the wind,” he said. “It's too windy today.” Then he glanced at the next terrace. His friend Meher's kite was riding the very same wind, and it was perfectly steady. So the wind was not to blame. Kabir crossed out his first idea.

He reeled his kite in and turned it over in his hands. On the left side sat a thick patch of tape from an old repair. Perhaps that side was too heavy? He cut a patch of the same size and stuck it on the right side. Up went the kite again, and this time it rose straight and true. His second idea had passed the test!

Kabir did not read a book about kites or ask an expert. He spotted a problem and came up with an idea about its cause. He checked the idea, dropped it when it failed and tried a better one (Fig. 1.6). This way of cracking a puzzle has a name: the scientific method (वैज्ञानिक विधि). Now that you know its name, you will start spotting it everywhere.

The steps of the scientific method

Let us replay Kabir's story in slow motion and give each move a name. Scientists use these same moves, whether they are studying kites, curd or comets (Fig. 1.7).

1. Observe. Use your senses, and tools such as a ruler or a hand lens, to gather observations (प्रेक्षण). Kabir saw his kite dive, again and again.
2. Question. Put the puzzle into words. “Why does my kite dive to the left?” is a clear question that you can work on.
3. Guess. Think up an explanation that could be checked. Scientists call it a hypothesis (परिकल्पना). “The left side is too heavy” is one.
4. Test. First make a prediction: if the guess is right, what will happen? Then find out. You can set up an experiment (प्रयोग), like taping the right side, or simply look again more carefully, like glancing at Meher's kite.
5. Analyse. Compare what happened with what you predicted. A match supports your guess. A mismatch sends you back to guess again.

Notice that the steps go round and round. A good answer often raises a new question, and a failed guess sends you back for another one. Real science loops like this all the time.

Test a guess yourself

Here is a guess that many people make: “All metals stick to magnets.” It sounds sensible. Iron nails stick, and so do steel pins, so why not every metal? Instead of arguing about it, a scientist would test it. Try it in Fig. 1.8.

Did the aluminium foil and the copper wire stick? They did not. A result like this shows that the guess needs changing. A better hypothesis would be: “Some metals, such as iron, steel and nickel, stick to magnets, but others do not.” You can test this new guess further in the chapter on magnets.

A fair test

Tests need to be fair. Suppose two identical hankies are washed together. You hang one in the sun, spread out. You hang the other in the shade, folded into four. The first one dries much faster. Was it the sunshine or the spreading out that made the difference? You cannot tell, because two things were different at the same time!

In a fair test (निष्पक्ष परीक्षण) you change only one thing and keep everything else the same. To find out whether sunshine matters, both hankies must be the same size, equally wet and spread out in the same way. Only their place, sun or shade, should be different (Fig. 1.9).

Now run a tiny investigation of your own. Fig. 1.10 takes you through every step: you observe, pick a question, make a prediction, set up a test and analyse what happened. Try making the test unfair on purpose, and see what the investigation tells you.

Everyone can be a scientist

Some people investigate the world as their full-time job. We call them scientists (वैज्ञानिक), and they study everything from germs to glaciers. Yet the method is not a secret club. Plenty of people who never wear a lab coat use exactly the same moves every day.

In Fig. 1.11, a doctor sees a child who has had a fever for three days. She suspects an infection and asks for a blood test. A farmer notices one patch of his field wilting. He guesses that water is not reaching it, walks along the channel and finds it blocked with mud. A cricket coach sees his bowler overstep the crease again and again. Is the run-up too short? He moves the starting mark back a little, and they watch the next over.

Parents do it too. When a baby keeps crying, a parent runs through possible causes. Is she hungry? Sleepy? Too hot? They try one thing at a time, a feed, a lullaby, a lighter blanket, and watch what happens.

Keep asking why

You might wonder why you need science lessons at all. Think of cricket. A cricketer who trains every day plays far better than one who picks up a bat once a year. Thinking like a scientist works the same way. Today you might fix a jammed zip. With practice, you could one day help bring clean water to a whole village. Where does that practice start? With two simple habits: staying curious, and looking at things carefully.

Looking is not the same as seeing. Try Fig. 1.12. At first glance it is just a wall in a courtyard. Look again, and questions pop up everywhere.

Why do ants walk in such a neat line? Why do the leaves of the touch-me-not plant (छुईमुई) fold up when you brush them? Why does moss grow only under the dripping tap? Careful looking turns an ordinary corner into a treasure hunt. Scientists have cracked these three already. Other puzzles have beaten everyone so far. Perhaps you will be the one to solve one of them.

Science is teamwork

Look at the list of names on a modern science report and you may count ten, a hundred, sometimes over a thousand. Big questions need many minds. One person is good at building equipment, another at spotting patterns, another at checking the sums. Your class can work as a team too.

Here is how sharing helps. Five groups in a class timed how long an ice cube took to melt in a steel bowl (Fig. 1.13). Four groups got between 18 and 22 minutes. Group D got just 8. When the class compared notes, they found that group D's bowl had been sitting in a patch of sunshine by the window. Alone, group D might have believed a wrong answer. Together, the class caught the mistake.

Questions that stay open

Here is a secret: even the best scientists have more questions than answers. Nobody yet knows exactly how life on Earth began, or what most of the universe is made of. So an open question is not a failure. It is a place to dig. Many of yours will be answered in the classes ahead, and a few may stay open much longer.

Meanwhile, keep your eyes open and your notebook handy. Follow the ants to see where they go. Notice how your shadow changes through the day. Wonder why the idli batter rises overnight. A scientist is simply someone who stays curious and enjoys the hunt for answers.