Scientific Learning

1. Grade 5
   Unit 1 Scientific Learning Is the round pumpkin heavier than the long cucumber? Your eyes can only guess. Find out like a scientist: look, test, ask, and measure.
2. Grade 6
   Unit 1 Scientific Learning Will it sink or float? Guess first, then test, and you are already doing science. And how long is a table, if every hand’s bitta is different?
3. Grade 7
   Unit 1 Scientific Learning Every discovery begins with someone who noticed something and asked why. How do you turn a question into an answer you can trust?
4. Grade 8
   Unit 1 Scientific Learning Science is a way of finding things out: by looking closely, testing fairly and asking many people. You can do all three yourself.
5. Grade 9
   Unit 1 Scientific Study Science is a careful way of finding things out, with numbers that reach from an atom to the Sun.
6. Grade 10
   Unit 1 Scientific Learning A good experiment is a fair test, and a good formula has to make sense in its units.

Information and Communication Technology

1. Grade 5
   Unit 2 Information and Communication Technology How does a warning from a mountain pasture reach every village at once? And how do we get a computer to type, draw and remember for us?
2. Grade 6
   Unit 2 Information and Communication Technology From the dhiki to the phone in your pocket, people have always made tools to make work easier. How do you make today’s tools work for you?
3. Grade 7
   Unit 2 Information and Communication Technology A phone, a search box and a spreadsheet can do amazing work for you, if you know how to use them well and how to stay safe while you do.
4. Grade 8
   Unit 2 Information and Communication Technology Messages, money and photos now travel as numbers. How do the machines that carry them work, and how do we stay safe among them?
5. Grade 9
   Unit 13 Information and Communication Technology Signals travel through the air and through space to connect the world. How do they work, and how do we use them wisely?
6. Grade 10
   Unit 13 Information and Communication Technology Every message, picture and song can be turned into numbers and sent anywhere, to be used well or badly.

Living Things and Their Structure

1. Grade 6
   Unit 3 Organisms and their Structure Why can’t a fish live on land, or a yak in the warm Terai? Every plant and animal has a body built for its own home and its own food.
2. Grade 7
   Unit 3 Organisms and their Structure A potato is a stem, a sponge is an animal, and you are made of trillions of cells. How is each living thing built for the life it leads?
3. Grade 8
   Unit 3 Living Beings and Their Structure Every living thing, from an ostrich to the microbes in gundruk, is built of cells, and scientists sort all life by what they are like.

Classification of Living Beings

1. Grade 5
   Unit 4 Classification of Living Beings How can anyone keep track of millions of living things? Sort them by clues: a backbone, feathers, a leaf’s veins, a seed that splits in two.
2. Grade 9
   Unit 2 Classification of Living Beings There are millions of kinds of living things. Sorting them into groups lets us name them, study them and understand them.
3. Grade 9
   Unit 3 Mushroom A mushroom is neither a plant nor an animal: a hidden web that feeds on dead things, and a food we can grow.
4. Grade 10
   Unit 2 Classification of Living Beings All life is one family tree, and sorting it shows how each living thing is related to the rest.
5. Grade 10
   Unit 3 Honey Bee A colony of honey bees works like one animal, every bee doing its part, and Nepal's bees feed us and our crops.

Life Processes and the Human Body

1. Grade 5
   Unit 5 Life Process Even while you sleep, you breathe and your body turns food into energy. What jobs keep every plant and animal alive?
2. Grade 6
   Unit 5 Life Process A plant makes its food out of air, water and sunlight. You can’t: so where does your dal bhat go, and how does it end up as you?
3. Grade 7
   Unit 5 Life Process Your heart beats and your lungs breathe without your thinking about it. How does a living thing, from an Amoeba to you, keep itself going?
4. Grade 8
   Unit 5 Life Process How living things make more of themselves, from one cell splitting in two to a seed reaching new ground and sprouting.
5. Grade 9
   Unit 5 Body Structure and Life Process Plants and animals are built of tissues working together, and nerves and hormones keep every part in step.
6. Grade 10
   Unit 5 Physiological Structure and Life Process The heart, blood and blood vessels carry life around the body every second. How do we keep them healthy?
7. Going Further
   6–8 Why Do Birds Sing and Flowers Smell Sweet? The magpie-robin isn’t singing for you, and the rhododendron isn’t red for you. So who is it all for?
8. Going Further
   6–8 Why Do Two Plants From the Same Field Grow So Differently? Same farmer, same field, same day: one maize plant taller than your father, one thin and pale. Seed or soil?
9. Going Further
   6–8 What Happens to the Dal Bhat You Eat? Yesterday’s dal bhat kept you warm and moved your legs, and a little of it is now you. How does rice become your arm?
10. Going Further
    6–8 How Does a Touch Reach Your Brain? Your lips jerk away from hot tea before you can think, and next day you blow on it first. What happened inside you?
11. Going Further
    9–12 How Does a Gene Make a Protein? Chew plain rice and it turns sweet, thanks to a tool built from instructions in four letters. How does a cell read them?
12. Going Further
    9–12 How Does Your Body Stay at 37 °C? Winter in Jumla or summer in the Terai, your inside stays almost the same. Feedback loops that keep it steady.
13. Going Further
    9–12 How Does One Cell Become a Whole Person? You began as one cell. How it became trillions, and how cells with the same DNA became skin, bone and brain.
14. Going Further
    9–12 How Does Food Become Energy, and Become You? Some of your dal bhat becomes your muscle, and much of it you breathe out. How does rice become energy, and become you?

Heredity and Evolution

1. Grade 9
   Unit 4 Evolution Living things have changed over millions of years, and fossils, our own bodies and the life around us show how.
2. Grade 10
   Unit 4 Heredity Why children look like their parents, but not exactly: how cells divide and pass on their instructions.
3. Going Further
   6–8 Why Do You Look Like Your Parents, but Not Exactly? Kittens of one mother, no two alike. A seed from a sweet apple tree grows sour apples, a twig from it sweet ones. Why?
4. Going Further
   6–8 How Do Snow Leopards Come to Fit the Mountains? Nobody designed the snow leopard, and none ever chose a longer tail. So how did it come to fit the mountains so well?
5. Going Further
   6–8 How Did Farmers Make Our Crops? Wild rice drops its grains at a touch; the rice you eat holds on. Farmers made it so, mostly without knowing how.
6. Going Further
   9–12 Why Aren’t You Exactly Like Your Brother or Sister? Same mother, same father, yet one is tall and curly-haired and the other isn’t. How different can brothers and sisters be?
7. Going Further
   9–12 How Does DNA Show That All Life Is Related? An oyster mushroom is more closely related to you than to a rhododendron. A mushroom has no bones, so how do we know?
8. Going Further
   9–12 Why Do Antibiotics Stop Working? The tablets that cured typhoid in Nepal for years stopped working. Nobody made a new disease, so what changed?
9. Going Further
   9–12 How Do New Species Begin, and End? The spiny babbler lives in Nepal and nowhere else; the blackbuck here fell to nine animals. How do species begin, and end?

Environment and Biodiversity

1. Grade 5
   Unit 3 Organisms and Environment Why do lizards hide all winter, and how do tomatoes grow in frost? All life needs the Sun’s heat and light, and we need energy that will last.
2. Grade 6
   Unit 4 Biodiversity and Environment Take the tigers away and the deer eat the forest bare. Every living thing in a place depends on the others, and on us.
3. Grade 7
   Unit 4 Biodiversity and Environment Why do yaks live in the Himalaya and rhinos in the Terai, and how can we use forests and water without using them up?
4. Grade 8
   Unit 4 Biodiversity and Environment Nepal is a small country, so why does it hold so much of the world's life, and what will it take to keep it?
5. Grade 9
   Unit 6 Nature and Environment Every living thing depends on others and on its surroundings, so a change in one place spreads through the whole.
6. Grade 10
   Unit 6 Nature and Environment People are changing the climate and the living world, and Nepal shows that things can also be put right.
7. Going Further
   6–8 Why Do Animal Numbers Rise and Fall? In 2020 the sky over the Terai filled with locusts that most years live alone in the desert. Where did so many come from?
8. Going Further
   6–8 Why Are There So Few Tigers? Chitwan has hundreds of deer and wild pigs for every tiger. Why doesn’t the forest fill up with its strongest hunters?
9. Going Further
   6–8 What Is a Forest Worth? No forest sends a bill for clean water, firm slopes or bees for the crops, so we forget, until it’s gone. What is it worth?
10. Going Further
    6–8 Why Is There Oil in Some Places but Not Others? Saudi Arabia has huge oil fields; Nepal has none. Why the Earth’s riches lie where they do, and how fast we use them up.
11. Going Further
    6–8 Can We Tell When Disaster Will Strike? Floods and storms often give warning; earthquakes don’t, yet. How can the past help us get ready for the next one?
12. Going Further
    6–8 How Do We Know How Dirty the Air Is? Kathmandu’s air is often far dirtier than is safe. How do we measure it, and tell whether a fix has really worked?
13. Going Further
    6–8 What Happens When There Are More of Us, Each Using More? The Kathmandu Valley’s wells are running down. Is it because there are more of us, or because each of us uses more?
14. Going Further
    6–8 Is the Earth Really Getting Warmer? One cold winter proves nothing. What do the world’s thermometers and its air really show, and what is causing it?
15. Going Further
    9–12 Can Life Run Without Oxygen? Yeast making jaand, your muscles in a sprint, microbes in a flooded paddy: life that gets its energy without oxygen.
16. Going Further
    9–12 How Many Tigers Can Chitwan Hold? Nepal’s wild tigers rose from 121 in 2009 to 429 in 2026. Can they keep growing? Carrying capacity in numbers.
17. Going Further
    9–12 Where Does a Fallen Leaf Go? A sal forest drops tonnes of leaves every year, yet its floor is never buried. Where do they all go?
18. Going Further
    9–12 Can a Forest Come Back? Hills left bare in the 1970s are green again under Nepal’s community forests. How ecosystems recover, and how to help.
19. Going Further
    9–12 Why Do Animals Live in Groups? Every pigeon in a flock competes with the others for grain, yet they stay together. Does the group really help each one?
20. Going Further
    9–12 Why Do People Live Where They Do? Kathmandu stands on the bed of an old lake, and its rich soil is why people came. What decides where people live?
21. Going Further
    9–12 Which Energy Should Nepal Use? In 2015 Nepal ran short of power and petrol at once. What should it build next, and which costs are worth paying?
22. Going Further
    9–12 Does the Fix Actually Work? Many valley brick kilns were rebuilt after 2015 to a zigzag design that burns less coal. Testing a fix with data.
23. Going Further
    9–12 How Many People Can the Earth Support? Over eight billion people, all fed from land and sea we share with millions of species. How many can the Earth hold?
24. Going Further
    9–12 What Will the Climate Be Like When You Are Grown Up? How warm will the world be, and how much Himalayan ice will be left, when you are grown up? And how can anyone know?

Force, Motion and Machines

1. Grade 6
   Unit 6 Force and Motion Are you sitting still, or rushing through space faster than a bullet? And how can one person tip over a one-tonne stone with an iron bar?
2. Grade 7
   Unit 6 Force and Motion Why can you walk 16 m and end up where you started? What pulls everything down, and why is holding a heavy load all day no work at all?
3. Grade 8
   Unit 6 Force and Motion Whether a thing is moving depends on who is watching, and a small force in the right place can lift a great weight.
4. Grade 9
   Unit 7 Force and Motion Why things start, stop and turn: three laws explain every push and pull around us.
5. Grade 9
   Unit 8 Simple Machine A simple machine never gives back more work than we put in, but it lets a small force do a big job.
6. Grade 10
   Unit 7 Motion and Force The same pull that drops an apple keeps the Moon in its orbit and holds the universe together.
7. Grade 10
   Unit 8 Pressure A push on a liquid or a gas spreads everywhere in it. That is how brakes work and why ships float.
8. Going Further
   6–8 Why Does a Rolling Ball Stop? A kicked football rolls to a stop. For 2,000 years the wisest people said it ran out of push. They were wrong.
9. Going Further
   6–8 Who Feels the Bigger Push in a Crash? A motorbike bumps a truck: the rider falls off, the truck driver hardly notices. So who pushed harder? Not who you think.
10. Going Further
    9–12 Why Do Airbags Save Lives? An egg dropped on stone breaks; on a blanket it may not, though it falls just as fast. Why does how it stops matter?
11. Going Further
    9–12 Why Is Gravity So Weak? The whole Earth pulls a scrap of paper down; a comb rubbed in your hair lifts it up, and wins. Why is gravity so weak?
12. Going Further
    9–12 Why Is Spider Silk So Strong? A thread thinner than a hair stops a flying fly, and weight for weight beats steel. Its secret isn’t what it’s made of.

Energy, Heat, Light and Sound

1. Grade 5
   Unit 7 Energy In a power cut at night, the room goes dark and the fan goes quiet. What are light, sound and electricity, and how can we use them safely?
2. Grade 6
   Unit 7 Energy in Daily Life Energy is never used up, only changed. Follow it from a lake to your light bulb, and from a madal to your ears.
3. Grade 7
   Unit 7 Energy in Daily Life Dal bhat, a bulb, hot tea, a shout: all of them run on energy. Where does it come from, and how does it reach us as heat, sound and light?
4. Grade 8
   Unit 7 Energy in Daily Life Heat, light and sound are energy on the move. This unit follows each of them on its way.
5. Grade 9
   Unit 9 Energy Nearly all the energy we use began as sunlight. Where does Nepal's come from, and how can we use it better?
6. Grade 9
   Unit 10 Wave Light, sound and radio are all waves, carrying energy and messages without carrying matter along.
7. Grade 10
   Unit 9 Heat Heat always flows from hot to cold, and how much it takes to warm something depends on what it is made of.
8. Grade 10
   Unit 10 Wave Light bends as it passes from one material into another, and that bending lets us see, make lenses and correct eyes.
9. Going Further
   6–8 Why Is Speeding So Dangerous? Hit at 65 km/h instead of 50, a person on foot is 4.5 times as likely to die. Why does a little more speed matter so much?
10. Going Further
    6–8 Where Does a Lifted Stone Keep Its Energy? Kulekhani’s lake sits still for months, yet holds enough energy to light homes all winter. Where is that energy kept?
11. Going Further
    6–8 Why Can You Hear Through a Wall but Not See Through It? The wedding drum next door booms through the wall, yet you can’t see a single light. Why does a wall stop only one?
12. Going Further
    6–8 Can You Build a Box That Keeps Ice Frozen All Day? On a hot day, ice melts by noon. Can you design a box that saves it until evening, and prove that it works?
13. Going Further
    9–12 Where Does the Energy Go When a Ball Bounces? Energy is never destroyed, yet a dropped ball bounces lower each time and then lies still. Where did its energy go?
14. Going Further
    9–12 Why Does Heat Never Flow from Cold to Hot? Hot chiya cools on the table; cold chiya never heats itself up, though no law of energy forbids it. So what does?
15. Going Further
    9–12 What Are Stars Made Of? Nobody has been to a star, yet we know what they’re made of. Learn to read the barcode hidden in starlight.
16. Going Further
    9–12 Is Light a Wave or a Stream of Particles? Light spreads and interferes like a wave, yet knocks electrons out of metal like a hail of particles.
17. Going Further
    9–12 Is Phone Radiation Dangerous? A WhatsApp message says the new phone tower will give children cancer. Is it right, and how can you judge for yourself?

Electricity and Magnetism

1. Grade 6
   Unit 8 Electricity and Magnetism How can a lemon make electricity, a nail become a magnet, and a thin wire save a house from fire?
2. Grade 7
   Unit 8 Electricity and Magnetism Why does a combed comb pick up paper, what makes lightning, and how do two small cells light a torch more brightly than one?
3. Grade 8
   Unit 8 Electricity and Magnetism The unseen pull of a magnet and the current in the walls: what they are, and how a house keeps us safe from them.
4. Grade 9
   Unit 11 Electricity What makes a current flow through a wire, and how it lights, heats and runs our homes.
5. Grade 10
   Unit 11 Electricity and Magnetism Electricity and magnetism are two sides of one thing, and the link between them runs motors and generators.
6. Going Further
   6–8 How Can Something Push Without Touching? A rubbed comb lifts paper and a magnet makes a pin leap, across an empty gap. What reaches across the space between?
7. Going Further
   9–12 How Do Magnets Push Without Touching? Two magnets jump together with a click, though nothing was burnt or wound up. Where did the energy of the jump come from?
8. Going Further
   9–12 How Much Electricity Can a Small Stream Make? A hill stream has turned the ghatta’s millstone for centuries; now it can light a village. How much power can it make?

Matter, Atoms and Reactions

1. Grade 5
   Unit 6 Matter Why does water take the shape of its glass, but a stone doesn’t? Everything around you is matter, and heat can change it.
2. Grade 6
   Unit 9 Matter Salt vanishes in water, yet the water still tastes salty. Where did it go, and how do you get it back out?
3. Grade 7
   Unit 9 Matter Why does a brick sink while a log floats, and what are the tiny pieces that everything around us is built from?
4. Grade 8
   Unit 9 Matter Everything is made of a few kinds of atom. What is inside an atom decides how it joins others, and the periodic table puts them in order.
5. Grade 9
   Unit 14 Atomic Structure and Chemical Bond Everything is built of atoms, and how their outer electrons are passed or shared decides how they join.
6. Grade 9
   Unit 15 Chemical Reaction In a chemical reaction no atom is made or lost: the same atoms are rearranged into new substances.
7. Grade 9
   Unit 16 Gases Hydrogen, oxygen and nitrogen are invisible, yet life can't do without them. And how the world saved the ozone layer.
8. Grade 10
   Unit 14 Classification of Elements The elements fall into a pattern, and the periodic table is so good it foretold elements no one had yet found.
9. Grade 10
   Unit 15 Chemical Reaction Reactions happen in a few kinds of ways, and we can make them go faster or slower.
10. Grade 10
    Unit 16 Gases Some gases keep us alive, some keep the Earth warm, and some, in the wrong place, turn rain into acid.
11. Going Further
    6–8 What Does a Molecule Look Like? Every grain of kitchen salt is a tiny cube, though nobody cut it. What shapes do atoms make when they join?
12. Going Further
    6–8 Where Does the Heat Go When Ice Melts? Heat a glass of melting ice and it stays at 0 °C until all the ice has gone. Where does the energy go?
13. Going Further
    6–8 Can You Make a Hand Warmer? A packet warms your hands with no fire or battery; a squeezed pack turns ice cold. Where does the heat come from?
14. Going Further
    9–12 Why Does Salt Melt at 801 °C but Ice at 0 °C? Water and methane molecules are almost the same size, yet water boils at 100 °C and methane at −162 °C. Why?
15. Going Further
    9–12 Why Do Some Reactions Get Hot? The gas in the cylinder is cold, and so is the air. Mix them, add a spark, and out roars heat. Where was it hiding?
16. Going Further
    9–12 What Makes a Reaction Go Faster? A fridge takes barely a tenth of the milk’s energy away, yet milk that would sour by evening keeps for days. Why?
17. Going Further
    9–12 Why Do Some Reactions Stop Halfway? Nitrogen and hydrogen over hot iron stop changing when only a quarter is ammonia, however long you wait. Why stop halfway?
18. Going Further
    9–12 How Do You Count Atoms by Weighing Them? Nobody counts the rice at the shop: they weigh it. Chemists count atoms the same way, though nobody can see one.
19. Going Further
    9–12 What Happens Inside a Nucleus When It Decays? Every second, thousands of atoms in your body become a different element, the alchemists’ dream. What happens inside them?
20. Going Further
    9–12 Where Is the Electron? Grade 9 draws electrons on neat circles. Nobody has ever seen one go round: so where is it, really?

Materials and Chemicals We Use

1. Grade 6
   Unit 10 Materials Used in Daily Life Soap, salt, baking soda, a steel spoon: you use dozens of materials every day. What makes each one right for its job, and when do they harm us?
2. Grade 7
   Unit 10 Materials Used in Daily Life How can you tell an acid from a base without tasting it, and why do we make wires of copper and wrap food in aluminium?
3. Grade 8
   Unit 10 Materials Used in Daily Life The chemistry of everyday things: what makes something sour or bitter, why some water is hard, and how we can tell.
4. Grade 9
   Unit 17 Metals and Non-metals Metals and non-metals behave in opposite ways, and that decides what each is good for, and what harms us.
5. Grade 9
   Unit 18 Carbon and its Compounds One element, carbon, makes diamonds, the lead of a pencil and every living thing.
6. Grade 9
   Unit 19 Materials used in Agriculture Plants need food too. Feeding the soil well gives good harvests without poisoning the land.
7. Grade 10
   Unit 17 Metals and Non-metals Metals lie hidden in rocks as ores, and getting them out pure is a long journey from mine to metal.
8. Grade 10
   Unit 18 Hydrocarbon and its Compounds Chains of carbon and hydrogen are our fuels, and adding other atoms to them makes alcohols and much more.
9. Grade 10
   Unit 19 Chemicals used in Daily Life The chemicals in our kitchens, fields and bathrooms make life easier, and some of them come at a cost.
10. Going Further
    6–8 Where Does Plastic Come From? A clear, hard water bottle began as black, sticky oil. How does one become the other, and at what cost?

Earth and Space

1. Grade 5
   Unit 8 The Earth and Space The Sun seems to cross the sky, and the Moon changes shape every night. Is the sky moving, or are we? Find out how the Earth spins and travels.
2. Grade 6
   Unit 11 The Earth and Space A handful of soil took centuries to make, and under it spins a hot, tilted ball racing round the Sun. Why does that bring us summer and winter?
3. Grade 7
   Unit 11 The Earth and Space Where does the stone under your feet come from, why does the Moon change shape, and how can we know years ahead when the Sun will go dark?
4. Grade 8
   Unit 11 The Earth and Universe Where did the Earth, life and the whole universe come from, and how do we know?
5. Grade 9
   Unit 12 The Universe Stars are born, shine and die, and the universe they live in had a beginning.
6. Grade 10
   Unit 12 Universe The universe is vast, old and still growing, and we can read its story in light.
7. Going Further
   6–8 How Do Rocks Tell Time? Geologists had put the Earth’s long history in order by the 1840s, before anyone could date a rock. How did they read it?
8. Going Further
   6–8 Why Is It Cold in Winter? Not because the Earth is farther from the Sun: in January it is closest. The real reason, and why Nepal’s days change length.
9. Going Further
   6–8 How Does One Rock Become Another? The top of Everest was once a sea floor. How does rock keep changing from one kind to another, and what keeps it going?
10. Going Further
    6–8 Do Continents Really Move? The same fossil leaf lies in rocks in India, Africa and Antarctica. How could it, unless they were once joined?
11. Going Further
    6–8 Where Does the Rain Come From? Kathmandu’s rain was in the Bay of Bengal days before. What lifted it here, and how do forecasters see it coming?
12. Going Further
    6–8 Why Is Pokhara So Wet and Mustang So Dry? Pokhara gets thirteen times Jomsom’s rain, though they are only 70 km apart. What decides how wet or dry a place is?
13. Going Further
    9–12 How Long Will the Sun Shine? A fire runs out of wood and a lamp runs out of oil. The Sun has shone for billions of years. How much longer can it go on?
14. Going Further
    9–12 How Do We Know the Universe Is Expanding? Nobody has ever seen a galaxy move, yet we know almost all of them are flying away from us. How can anyone know?
15. Going Further
    9–12 Where Did the Atoms in Your Body Come From? Not one atom of a bride’s gold, or of the iron in your blood, was made on the Earth. So where were they made?
16. Going Further
    9–12 Why Don’t Satellites Fall Down? They do: they fall all the time and keep missing. Using Newton’s law to work out how fast and how long each orbit takes.
17. Going Further
    9–12 Why Is the Sea Floor So Young? Almost no sea floor is over 200 million years old, yet some continental rock is 4 billion. Plate tectonics explains it.
18. Going Further
    9–12 How Old Is the Earth? Nobody saw the Earth form, yet tiny crystals in Trishuli sand carry clocks that have ticked ever since. How old is it?
19. Going Further
    9–12 Why Is Everest Still Rising? Something is pushing a whole country north and lifting Everest every year. Nobody has ever been down to see what.
20. Going Further
    9–12 What Does Water Do to Rock? Rock seems the hardest thing there is, and water the softest. Yet water carved Pokhara’s caves and gorges. How?
21. Going Further
    9–12 Why Has the Climate Changed Before? Nobody burned coal in an ice age, and nobody stopped burning it to end one. So what changed the climate before us?
22. Going Further
    9–12 Can One Change Set Off Many More? Bare rock melts the snow around it, which bares more rock. When does one change set off more, and when does it die down?
23. Going Further
    9–12 Where Does the Carbon Go? A cylinder of cooking gas sends 43 kg of CO₂ into the air, but only about half of it stays there. Where does the rest go?
24. Going Further
    9–12 How Did Life Change the Air? The young Earth’s air had almost no oxygen. Bacteria made it, and changed rocks, seas and what could live.
25. Going Further
    9–12 Can You Design an Earthquake-Safe House? Nepal’s 2015 earthquake destroyed about half a million homes. Can we build homes that the next one won’t knock down?

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