Patterns

Join the dots

What Are Constellations?

Constellations are shapes we drew on the sky — the stars are not really grouped.

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A very old puzzle

Why Is the Night Sky Dark?

The night sky is dark because the universe is young and still expanding.

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Three things in a line

What Happens in an Eclipse?

An eclipse is one space rock's shadow landing on another.

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You live inside it

What Is the Milky Way?

The Milky Way is our galaxy — and we see it as a band because we are inside it.

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It was never a night object

Why Can You See the Moon in Daytime?

The Moon is often up in daytime, and you can see it whenever it is bright enough to beat the blue sky.

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Same ball, different view

Why the Moon Changes Shape

Half the Moon is always lit — phases are how much of that half faces you.

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Falling without ever landing

What Is an Orbit?

An orbit is a permanent fall: move sideways fast enough and the ground curves away as fast as you drop towards it.

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Falling forever

Why Planets Orbit the Sun

Planets fall toward the Sun but move sideways fast enough to keep missing it.

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Light, sorted

Where Do Colours Come From?

Colour is which parts of white light an object bounces back at your eyes.

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Waves bunched and stretched

Why Does a Siren Change Pitch as It Passes?

A passing siren drops in pitch because its waves arrive bunched while approaching and stretched once leaving.

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Trading speed for strength

How Do Gears Work?

Gears let you trade speed for force by pairing wheels of different sizes.

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Nothing changes for free

Why Do Things Keep Moving?

Inertia is an object's refusal to change speed or direction on its own.

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Invisible reach

How Do Magnets Work?

A magnet works because its atoms are all lined up in the same direction.

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A very smooth wall

How Do Mirrors Work?

Mirrors work because their surface is smooth enough to bounce light without scrambling it.

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A reliable swing

Why Does a Pendulum Keep Time?

A pendulum keeps time because its swing length depends only on the string, not the size of the swing.

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Counting wiggles

What Makes a Sound High or Low?

Pitch is how fast something vibrates — fast means high, slow means low.

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Same family, different size

Is Radio Really a Kind of Light?

Radio is genuinely light, just with waves metres long instead of fractions of a millimetre.

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Light coming back

Why Can You See Yourself?

Reflection is light bouncing off a surface at the same angle it arrived.

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Pushing in time

Why Does One Note Rattle the Window?

Resonance happens when a sound matches something's natural rhythm, so every wave adds to the last.

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Light in a straight line

Why Do Shadows Happen?

A shadow is the place light could not reach because something was in the way.

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Squeeze and stretch

What Does a Sound Wave Look Like?

A sound wave is alternating bands of squeezed and spread-out air travelling along.

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Nothing is pushing it out

Why Does the Water Stay in the Bucket?

Swung water stays in because it keeps moving straight while the bucket curves into its path.

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Wobbling back to the middle

Why Do Things Vibrate?

Vibration happens when something springy is pushed out of shape and overshoots on the way back.

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Rolling beats dragging

Why Are Wheels So Good?

Wheels work because rolling replaces sliding friction with almost none.

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A fluffy seed parachute

How Does a Plant Become a T-Shirt?

Cotton fibres are seed hairs that get combed straight, twisted into thread, and woven into cloth.

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One kind of atom, all the way through

Why Is There a Table of Everything?

An element is stuff made of just one kind of atom, and the whole world is built from about ninety of them.

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Twist turns short fibres into long ones

How Does Fluff Become Thread?

Thread is short fibres twisted until friction holds them together as one continuous strand.

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Twist, and twist again

Why Is a Rope Stronger Than Its Threads?

A rope is strong because twisting makes every fibre squeeze its neighbours, so pulling only tightens the grip.

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A caterpillar's sleeping bag

Where Does Silk Come From?

Silk is one long thread a caterpillar spins to make its cocoon, unwound whole and woven into cloth.

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The same atom, two arrangements

Why Is Diamond Hard and Pencil Lead Soft?

Diamond and pencil lead are the same atom. Only the pattern of the bonds is different, and it changes everything.

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A recipe with no judgement

What Makes Something an Algorithm?

An algorithm is a sequence of steps precise enough that a machine can follow it without judgement.

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Turn, not length

What Is an Angle Actually Measuring?

An angle measures amount of turn between two directions, so longer arms do not make a bigger angle.

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Counting without counting

Why Are Rows and Columns Useful?

An array arranges things in rows and columns so you can multiply instead of count.

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On and off is enough

How Do Computers Count With Only Two Digits?

Computers count in binary because a switch has just two states, and place value does the rest.

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Two clocks that do not match

Why Does a Year Have 365 Days?

A year is 365 days because that is how many spins Earth makes per orbit.

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More orders than atoms nearby

Has Anyone Ever Had This Hand Before?

A pack of cards has so many possible orders that a well-shuffled deck has probably never existed before.

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Objects have no memory

Why Does a Coin Not Owe You Heads?

Chance has no memory: past results cannot influence a fair coin or die on its next throw.

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One thing, one word

How Does Counting Work?

Counting works by pairing each object with one number word, in a fixed order.

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More ways to get there

Why Is Seven the Commonest Roll?

Seven comes up most on two dice because more combinations add up to it than to any other total.

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Fair shares

How Does Division Work?

Division shares a total into equal groups and tells you how much each group gets.

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Two of the same

What Does Doubling Mean?

Doubling means adding a number to itself, and it grows shockingly fast.

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Small steps that stop being small

Why Does Doubling Get Out of Hand?

Repeated doubling grows slowly at first and then explodes, because each step is bigger than everything before it.

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Never running out

What Is Infinity?

Infinity means there is no end — you can always add one more.

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One giant number spoils it

Why Is the Average Sometimes a Lie?

An average is dragged by extreme values, while the middle value ignores them.

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Many equal groups

What Does Multiplying Do?

Multiplying is repeated adding of equal groups, done in a single step.

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Can everyone find a partner?

Odd and Even Numbers

Even numbers split into pairs with none left over; odd numbers always leave one.

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Something that repeats

What Is a Pattern?

A pattern is a repeating rule, and finding the rule lets you predict what comes next.

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Position carries meaning

Why Does 25 Mean Twenty-Five?

In our number system, where a digit sits decides how much it is worth.

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No rectangle but a line

Which Numbers Refuse to Split?

Primes are numbers that cannot be split into equal groups, so they only ever form one long row.

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You are usually in the slow one

Why Is the Other Queue Always Faster?

With several queues, the odds are against yours being the quickest — and one shared queue fixes it.

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Two out of a million is still nearly none

Why Does Buying Two Tickets Barely Help?

Doubling your tickets doubles a chance so small that twice it is still almost nothing.

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Position is not distance

Why Do Rankings Change When Nothing Does?

A ranking keeps only the order, discarding how far apart the things really are.

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The bit left over

What Is a Remainder?

A remainder is what is left after making as many equal groups as possible.

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Balance beat arithmetic

Why Do Clocks Sometimes Say IIII?

Clocks use IIII instead of IV because the heavier shape balances VIII across the dial.

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Sorted by rules

Why Do Shapes Have Names?

Shape names are definitions — a checklist of sides, angles and corners.

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Faster than one at a time

Counting in Jumps

Skip counting means counting in equal jumps instead of one at a time.

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Order makes finding easy

Why Do We Sort Things?

Sorting things into order makes finding any one of them far faster.

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Two matching halves

What Is Symmetry?

Symmetry means a shape matches itself when folded or turned.

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Counting without losing your place

Why Count in Groups of Five?

Tally marks bundle counts into fives so you can add up groups instead of recounting one by one.

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Shortcuts, not memory

What Patterns Hide in the Times Tables?

The times tables hide patterns that turn dozens of separate facts into a handful of shortcuts.

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A number for nothing

What Is Zero?

Zero is the number that counts nothing, and it makes big numbers possible.

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A fast band steering the weather

What Is the River of Wind Up High?

Jet streams are ribbons of fast high wind formed where warm and cold air meet, and they steer our weather.

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Atoms in formation

What Is a Mineral?

A mineral is a natural solid with a fixed recipe and a repeating atomic pattern.

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Salt arrives and never leaves

Why Is the Sea Salty?

The sea is salty because rivers deliver salt and only fresh water evaporates out.

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Nothing is permanent

Can a Rock Turn Into a Different Rock?

Rocks continually change type, as heat, pressure and weathering recycle them into one another.

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Water eats red light

Why Is the Sea Blue?

The sea looks blue because water absorbs red light quickly and only blue makes it back to your eyes.

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Six arms, one journey

Why Is Every Snowflake Different?

Ice always grows six ways, but each flake's journey through the cloud is unique.

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A loop with no end

Where Does Water Go?

Water evaporates, forms clouds, rains down and flows back to the sea, forever.

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Energy moving, water staying

Do Waves Carry Water Along?

Ocean waves carry energy across the water while the water itself circles in place.

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Lines, triangles and half-circles

How Do You Read a Weather Map?

Weather map lines join places of equal pressure, and the fronts show where air masses collide.

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The one blush you cannot fake

Why Do You Go Red When You Are Embarrassed?

Blushing is blood vessels in your face opening on their own — a signal you cannot start, stop, or fake.

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Predicting, not just reacting

What Does Your Brain Do?

The brain constantly predicts what is happening and corrects itself using the senses.

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A brain rehearsing offline

Why Do We Dream?

Dreams happen while a sleeping brain replays and sorts the day, with the body held still.

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A pump squeezing

What Is a Heartbeat?

A heartbeat is a muscle squeezing blood around your body's loop.

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Guess everything, keep what works

How Does Your Body Fight a New Germ?

Your immune system makes millions of random shapes in advance, then mass-produces whichever one happens to fit the invader.

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A recipe, copied twice

Why Do You Look Like Your Parents?

You inherit half your instructions from each parent, shuffled into a brand new combination.

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Drowning out one signal with another

Why Does Scratching Feel So Good?

Itch travels on its own slow nerves, and scratching drowns it out with pain signals your spinal cord prioritises.

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The tip of something bigger

What Is a Mushroom?

A mushroom is the spore-making fruit of a much larger underground fungus network.

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An alarm, not a measurement

Why Does It Hurt?

Pain is an alarm your brain chooses to sound — which is why the same injury can hurt very differently.

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Pollen reaching the right place

What Is Pollination?

Pollination is pollen moving between flowers so that seeds can be made.

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A net, cast in seconds

How Does a Cut Stop Bleeding?

A cut stops bleeding when platelets plug the hole and a protein mesh forms across it, trapping blood cells into a scab.

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Maintenance time

Why Do We Sleep?

Sleep is when your body repairs and your brain sorts and stores the day.

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Five basics, plus your nose

How Does Taste Work?

The tongue detects five basic tastes; the rest of flavour is smell.

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Three kinds of tear

Why Do We Cry?

There are three kinds of tears: constant maintenance, emergency rinsing, and emotional ones.

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Several senses at once

How Does Touch Work?

Touch is several different senses working together in your skin.

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A filter, not a plan

Why Do Animals Fit Where They Live?

Animals fit their homes because the variations that survived best got passed on, over and over.

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Chemical trails

How Do Ants Find Food?

Ants find food by laying scent trails that automatically favour the shortest path.

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Instinct plus practice

How Do Birds Build Nests?

Birds build nests by instinct, and improve at it with practice.

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Rebuilt from the inside

How Does a Caterpillar Become a Butterfly?

A caterpillar dissolves inside its chrysalis and is rebuilt as a butterfly.

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Breaking up the outline

How Does Camouflage Work?

Camouflage works by breaking up an animal's outline so no shape is recognised.

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Following the food

Why Do Birds Migrate?

Birds migrate to follow food supplies that move with the seasons.

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A very old rule, badly broken

Why Do Moths Fly Into Lights?

Moths navigate by keeping a distant light at a fixed angle — a rule that works with the moon and fails badly with a lamp.

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Only some threads are glued

Why Don't Spiders Stick to Their Own Webs?

Spiders avoid sticking because only some web threads are coated in glue.

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An animal built the wrong way round

How Does a Starfish Grow a New Arm?

A starfish walks on hundreds of tiny water-powered feet, has no brain or blood, and can regrow a lost arm.

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Nobody is in charge

How Does a Flock Turn All at Once?

A flock, shoal or swarm moves as one because each animal follows a few simple rules about its nearest neighbours.

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A skin that shoves the air

How Does a Drum Make a Sound?

A drum's stretched skin is hit, shudders, and shoves the air — with the shell shaping how long and low it rings.

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Sound coming back

What Is an Echo?

An echo is sound reflecting off a surface and returning to you delayed.

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Nothing left to absorb sound

Why Are Empty Rooms So Echoey?

Empty rooms echo because there is nothing soft left to absorb the reflected sound.

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Ridges that grip and feel

Why Do We Have Fingerprints?

Fingerprint ridges improve grip on wet surfaces and sharpen your sense of touch.

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Thickness, tightness, length

Why Do Guitar Strings Sound Different?

A string's note depends on how thick, how tight and how long it is — and a guitar lets you change all three.

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Waves that overlap themselves

Why Does a Microwave Heat Unevenly?

Microwaves bounce off the metal walls and overlap, creating fixed hot and cold spots.

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Every mix absorbs more

Why Does Mixing Paint Make Brown?

Mixed paints absorb more and more light, so the result heads towards brown.

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Eighty-eight little catapults

What Happens Inside a Piano?

A piano key throws a felt hammer at a string and releases it in mid-air, so the note can ring freely.

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Colours bending differently

What Does a Prism Do?

A prism splits white light into colours because each colour bends differently.

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Notes that share their wobbles

Why Does Singing Together Sound Good?

Notes sound good together when their vibrations fit in simple whole-number ratios, so the waves line up rather than clash.

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Light bouncing off two surfaces

Why Are Soap Bubbles Colourful?

Bubble colours come from light reflecting off both surfaces of the film and interfering.

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Pushing in time

How Do You Make a Swing Go Higher?

Pumping works because small pushes timed to a swing's natural rhythm build up over many arcs.

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Your brain saw it coming

Why Can't You Tickle Yourself?

You cannot tickle yourself because your brain predicts your own touch and cancels the surprise.

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The same note, a different mix

Why Does a Piano Not Sound Like a Violin?

Instruments differ because each adds a different mix of quieter extra notes on top of the one being played.

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Constant, invisible steering

Why Does a Moving Bike Stay Up?

A moving bike stays up because tipping steers the front wheel into the fall, and the curve pushes it upright again.

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Electricity needs a full loop

Why Does a Switch Turn Things On?

A switch works because electricity needs an unbroken loop, and opening a gap of air stops the whole thing.

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Something that always takes the same time

How Does a Clock Know When a Second Has Passed?

A clock finds something that always takes the same time, counts the repeats, and shows the total.

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A desk and a filing cabinet

Where Does a Computer Keep Things?

A computer uses fast memory that empties when the power goes, and slower storage that keeps things permanently.

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Instructions, and nothing but

What Is a Computer Program?

A program is a list of exact instructions a computer follows in order, with tests and repeats to change the path.

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A relay, not a delivery

How Does an Email Find You?

An email is passed between servers, sorted by the part after the @, and waits on a server until your device collects it.

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Under the floor and back

Where Do Escalator Steps Go at the Top?

Escalator steps never end: they flatten at the top, travel back underneath, and come up again.

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Millions of tiny corrections

How Does a Computer Learn?

A computer learns by guessing, being told how wrong it was, and nudging its own numbers — millions of times over.

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Somebody else's computer

Where Does a Website Actually Live?

A website lives as files on a real computer, and reaches you as small addressed packets passed router to router.

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A set of heights, not a shape

Why Does Only One Key Fit?

Only one key fits because each notch must lift its own pin to exactly the right height.

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Guessing is done by machine

Why Do Passwords Have to Be Long?

Passwords must be long because computers guess billions per second, and each extra character multiplies the work.

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Sense, decide, move

What Makes Something a Robot?

A robot senses the world, decides what to do about it, and moves — and it is the deciding that makes it a robot.

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Two threads that catch each other

How Does a Sewing Machine Stitch?

A sewing machine uses two threads: the needle pushes a loop under the cloth and a hidden second thread is caught inside it.

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A switch that feels the room

How Does a Heater Know When to Stop?

A thermostat is just a switch that temperature opens and closes, which is why a room drifts slowly above and below the number you set.

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A wire loop under the tarmac

How Does the Road Know You Are Waiting?

Traffic lights often notice you because a wire loop buried in the road detects your car's metal.

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Redrawn sixty times a second

How Does a Video Game Work?

A game reads your controls, works out the new state of its world, and draws a fresh picture — sixty times a second.

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Radio you cannot hear

How Does the Internet Cross a Room?

Wifi is radio: data rides on a wave that is wobbled in a pattern your phone knows how to read back.

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