Explore every explainer

📖 storybook How does a song fly through the air into your radio? wavessoundphysics Discover

📖 storybook Why is the sky blue? lightcolorsky Discover

📖 storybook Why doesn't a whole town get sick at once? germsspreadhealth Discover

📖 storybook Why does ice float? waterdensitystates of matterice Discover

📖 storybook Why do tiny things grow huge? growthmoneymathdoubling Discover

📖 storybook Why is it hot in summer and cold in winter? spaceearthlightseasons Discover

📖 storybook Do heavy things really fall faster than light ones? gravitymotionair Discover

📖 storybook Why are heavy things hard to push? motionforceinertia Discover

📖 storybook WiFi, Bluetooth, infrared — why does a TV remote need to point, but your phone doesn't? wavessignalswireless Discover

📖 storybook How does a glass screen know exactly where your finger is? electricitysensestech Discover

📖 storybook Why does WiFi slow down when busy? networksinternetsharing Discover

📖 storybook How does your phone know exactly where you are? spacesatellitesdistance Discover

📖 storybook What does a microwave actually heat? waveswaterheat Discover

What happens when a headphone plays a second sound? soundwavesinterference Discover

📖 storybook Is it harder to START a box sliding or to KEEP it sliding? frictionforcemotion Discover

Why do your shoes grip the floor but slip on ice? frictionmotionforce Discover

📖 storybook Why can a tiny kid lift a giant grown-up on a seesaw? leversbalanceforce Discover

📖 storybook Why do tightrope walkers carry a long pole? balancemotionforce Discover

📖 storybook Does the shape of a piece of steel decide if it floats? floatingdensitypressurewater Discover

Why does a balloon get squished when you dive deep in a pool? pressurefloatingforce Discover

Why do two magnets sometimes snap together and sometimes shove apart? magnetsforcefields Discover

📖 storybook Why does a ball on a string fly off the second you let go? motionforceinertia Discover

📖 storybook Why does a moving bike stay up? balancemotionspin Discover

What happens when you blow as hard as you can between two hanging soda cans? pressureairforce Discover

What does heating do to the air in a hot-air balloon? floatingpressureheat Discover

Why does a bulb only light up when the wire makes a full loop? electricitycircuitsforce Discover

Why do holiday lights all go dark when one bulb dies, but house lights don't? electricitycircuitsphysics Discover

📖 storybook Why does rubbing a balloon on your hair make it stick to the wall? electricityforcecharge Discover

📖 storybook Why does a moving magnet make power? magnetselectricitymotion Discover

📖 storybook Why does a spoon look bent in water? lightrefractionlenses Discover

Why can't you see around a corner, but you can hear around one? soundwavesdiffraction Discover

Why does mixing all the paint colors make brown, but all the lights make white? colorlightmixing Discover

Why can a singer shatter a glass with just the right note? soundresonancepitch Discover

If you dissolve a whole sugar cube in water, does the water weigh more? dissolvingmassconservation Discover

Why does hot cocoa mix in fast but cold milk leaves clumps? dissolvingheatspeed Discover

Can you keep stirring sugar into water forever? dissolvingsaturationlimits Discover

Why does a metal spoon feel colder than a wooden one sitting right next to it? heatmaterialsconduction Discover

Why do clouds float if they are full of water? weathercloudswaterair Discover

Why does it rain instead of just staying cloudy forever? weatherraincloudstemperature Discover

Why does wind blow from one place to another? weatherwindairpressure Discover

Why do you see lightning way before you hear the thunder? weatherthunderlightsound Discover

Why does the sea have a high tide and a low tide every day? oceanstidesmoongravity Discover

Why do you breathe faster when you run? breathingbodyoxygen Discover

Why does your heart beat in two thumps? heartbloodbody Discover

Does your own hand tickle you as much as a friend's? brainsensesneurons Discover

Why do you get dizzy after spinning? earsbalancebrain Discover

If everyone is driving fine and nobody crashes, how does a traffic jam appear out of nowhere? trafficfeedbacksystems Discover

📖 storybook Is a coin that just landed heads five times 'due' for tails? probabilityrandomnessluck Discover

If most buses run half-empty, what kind of bus does a random rider land on? averagesprobabilityeveryday Discover

Two gears, one big and one small — which spins faster, and can gears ever give you free speed? gearsratiosmachines Discover

How does a computer remember things even after you turn it off? memorycomputerselectricity Discover

Why does a parachute let you fall slowly when a rock just drops? airgravitymotion Discover

Why is it easier to lift a heavy bucket from a well with a wheel on top? machinesforcesimple-machines Discover

Two sheets of the same paper, same weight — do they fall at the same speed? airgravitymotion Discover

Why does a wide tractor tire roll over mud that a skinny bike tire sinks into? pressureforcesurfaces Discover

Why does a roller coaster need a big first hill to make it all the way around? motiongravityenergy Discover

Why does a rainbow always curve, and could you ever reach its end? lightcolorrainbows Discover

Why does a pencil's shadow have a fuzzy edge sometimes and a sharp edge other times? lightshadowsoptics Discover

📖 storybook Why does a police siren change its note as it races past you? soundwavesdoppler Discover

Why do bendy glass threads carry far more of your video call across the world without it fading? lightfiberreflection Discover

Why is a laser pointer a tiny dot far away but a flashlight is just a blob? lightlaserswaves Discover

Why does a magnifying glass flip the world upside down when you back it away? lightlensesoptics Discover

What happens when two identical sounds overlap? soundwavesinterference Discover

Why does a thin soap bubble swirl with rainbow colors when soapy water is clear? lightcolorinterference Discover

Why does plucking a tighter guitar string make a higher note? soundmusicpitch Discover

Why does a red apple turn black under a green light? colorlightperception Discover

Why does a sound die out fast in a small room but echo forever in a cave? soundechoesreflection Discover

Why does the moon look huge near the horizon but tiny up high? lightperceptionoptics Discover

Why does shaking a rope fast make tiny ripples but shaking it slow makes big rolls? wavesphysicssound Discover

Why does sugar vanish in water but sand just sits there? dissolvingwaterstates of matter Discover

Why does an iron nail turn orange and crumbly but a gold ring never does? rustmetalsoxygen Discover

Why does lemon juice fizz on baking soda but water just sits there? acidsbasesreactions Discover

📖 storybook Why does soap wash off greasy hands but water alone just rolls off the grease? soapwatermolecules Discover

📖 storybook Why does a candle flame die under a glass but burn forever in the open? fireoxygencombustion Discover

📖 storybook Why do crystals have flat sides? crystalsshapesdissolving Discover

Why does oil and vinegar split apart no matter how hard you shake them? mixingoilwater Discover

Why does white glue dry hard but stay gooey in the bottle? gluedryingstates of matter Discover

Why does red cabbage juice turn pink in lemon and green in soap? acidsbasesindicators Discover

Why does a steel ship float when a steel marble sinks? densityfloatingshapes Discover

Why does steam puff out of a pot but you can't see it right at the spout? states of matterevaporationwater Discover

Why does a cut apple turn brown — and can you stop it? oxygenreactionsrust Discover

Why does freezer ice turn out cloudy but fancy ice is crystal clear? freezingcrystalsstates of matter Discover

Why does a balloon stretch huge but a clay ball just splats? materialselasticitymolecules Discover

Why does salt melt the ice on a sidewalk but sugar barely helps? dissolvingfreezingstates of matter Discover

Why does a cup of mixed colored sand un-mix when you shake it? mixingmaterialssize Discover

Why does hand sanitizer feel freezing cold but water doesn't? evaporationheatstates of matter Discover

Why does a wet sandcastle hold its shape but dry sand just slides flat? materialswaterstates of matter Discover

Why does the Moon change shape every night? spacemoonlightorbits Discover

Why isn't there an eclipse every single month? spaceeclipsesmoonorbits Discover

Why does a volcano explode instead of just oozing? earthvolcanoespressuregas Discover

Why does the day stay light longer in summer? earthseasonsday lengthsunlight Discover

Why doesn't the Moon just fall down onto us? spaceorbitsgravitymoon Discover

Why does it get colder the higher up a mountain you go? weathertemperatureairpressure Discover

Why does a hurricane spin in a circle? weatherhurricaneswindearth Discover

Why does the ocean stay salty but rain is fresh? oceanswatersaltweather Discover

Why does a planet's year get longer the farther out it is? spaceorbitsgravityplanets Discover

Why does fog appear in the morning and then vanish? weatherfogtemperaturewater Discover

Why do astronauts float if there's still gravity up there? spacegravityorbitsastronauts Discover

Why does the wind near the coast switch direction between day and night? weatherwindoceanstemperature Discover

Why do hailstones grow big in summer, the hottest time of year? weatherhailcloudswind Discover

Why is it pitch dark at night when space is full of stars? spacestarslightuniverse Discover

Why does the wind make giant waves out at sea but not in a pond? oceanswaveswindwater Discover

Why does dropping air pressure tell you a storm is coming? weatherpressurestormsair Discover

How does your ear tell a high note from a low note? earssoundsenses Discover

Why does poking your skin sometimes hurt and sometimes just ache a beat later? neuronssensesbody Discover

What decides whether a cut heals clean or leaves a scar? skinhealingbody Discover

Why don't your bones snap when you jump? bonesbodystructure Discover

Why does your arm only pull, never push? musclesbodymovement Discover

Why do your eyes take a minute to see in the dark? eyessenseslight Discover

Why does sugar give you energy but you can't eat just sugar? foodenergybody Discover

Why does your body remember a germ it already beat? immune systemgermshealth Discover

Why does a wound get red and puffy when it's healing? immune systemhealingbody Discover

Is sunlight or water keeping this plant alive? plantsphotosynthesisenergy Discover

Where does a giant tree's wood actually come from? plantsphotosynthesisair Discover

Why do moths near cities turn dark? evolutionanimalssurvival Discover

Why does washing your hands stop the spread but a sneeze doesn't? germscontagionhealth Discover

Deadly vs fast-spreading — which germ takes over a town? germscontagionevolution Discover

Why does cold water feel colder than cold air at the same temperature? skinsensesheatbody Discover

Why can you hold your breath longer after taking fast deep breaths first? breathingbodyoxygen Discover

What makes a swing go higher — a big push, or the right timing? rhythmpatternsfeedback Discover

Why does one line at the bank beat a separate line for each teller? queuesaveragessystems Discover

Why can a thermostat (or a body) hold steady, but a microphone near its speaker screams? feedbacksystemscontrol Discover

Why do fireflies (and clapping crowds) end up blinking all together with no leader? networksfeedbackpatterns Discover

Why does a tiny rule, repeated over and over, make a giant detailed pattern? patternsfractalsinfinity Discover

Why does a sandpile, dropped one grain at a time, suddenly avalanche — and you can't say which grain did it? systemsfeedbackpatterns Discover

In a room of 30 kids, what are the odds two of them share a birthday? probabilitypatternscounting Discover

Why does cutting one wire sometimes take down the whole internet, and sometimes nothing at all? networkssystemsresilience Discover

📖 storybook What does a line of reflection symmetry guarantee? symmetrypatternsshapes Discover

Can you really fit ALL the counting numbers into the spaces between 0 and 1? infinitycountinglogic Discover

If you guess on a 3-door game show, should you switch doors after a hint? probabilitylogicgames Discover

Why do gossip, viral videos, and rumors blow up fast at first, then suddenly stall? networksfeedbackspread Discover

Two friends build a secret number over a line a spy is listening to — how can they end up sharing a number the spy can't make? encryptionsecretslogic Discover

If everyone throws their hat in a pile and grabs one at random, will someone still get their own? probabilitycountingpatterns Discover

Why does one person staying home from a party tip it from packed to empty? systemsfeedbacksocial Discover

Can you tell if a long string of numbers is real randomness or a person faking it? randomnesspatternsprobability Discover

Why does adding a brand-new road sometimes make EVERYONE'S drive slower? networkssystemstraffic Discover

How do you split a cake so nobody feels cheated? fairnessstrategysharing Discover

Can you mix two photos so a stranger can't read them, but your friend can? encryptionsecretslogic Discover

What does spinning do to a top that's about to fall over? balancemotionspin Discover

Why doesn't the water spill when you swing a bucket over your head? motionforcegravity Discover

Why does some thunder crack but other thunder rumbles? soundwavesphysics Discover

Why are two eyes better than one? eyessensesdepth Discover

Up close, what is a screen picture made of? screenscolorlighttechnology Discover

📖 storybook How does a phone shrink a huge photo small enough to send in a flash? compressionfilescomputerspixels Discover

📖 storybook What's the fastest way to find one name in a giant sorted list? searchingalgorithmscomputers Discover

📖 storybook How can a damaged message heal itself? informationerror correctioncodespatterns Discover

📖 storybook What does going first really buy in tic-tac-toe? gamesstrategyfairnesslogic Discover

📖 storybook How long is a coastline — and would two people ever measure the same number? fractalsmeasurementmapsmath Discover

📖 storybook Can stacked liquids catch an object that sinks in water? densityliquidsfloating Discover

📖 storybook How do temperature and surface area work together to change fizz speed? chemistryreactionstemperaturesurface area Discover

📖 storybook Why can a safe sealed process become warmer or cooler? chemistryreactionsheatenergy Discover

📖 storybook How can soap change the pull across a water surface? surface tensionwatersoap Discover

📖 storybook Why can cornstarch goo feel solid and liquid? materialsnon-newtonianstates of matterspeed Discover

📖 storybook What happens to a birthday candle's smoke right after you blow it out? firecandlesfuelchemistry Discover

📖 storybook How can one eye miss a patch while the world still looks complete? eyesvisionbrainbody Discover

Stare hard at a colored shape, then look away — what shows up? eyescolorvision Discover

📖 storybook The Moon keeps one face toward us — so is it spinning, or frozen still? moonorbitspace Discover

📖 storybook Why do ocean waves only crash and break when they reach the shore? wavesoceanwaterbeach Discover

📖 storybook How do collision history and source shape sand grains? rockserosionbeachesearth Discover

📖 storybook How does the Sun's gravity change with distance? gravityspacesundistance Discover

📖 storybook What happens when a spinning skater pulls her arms in? spinmotionphysicsskating Discover

If the sky's blue comes from bouncing light, why aren't clouds blue too? lightcolorcloudsweather Discover

📖 storybook How does a thermometer know how hot it is? heatparticlesmeasuringkitchen Discover

📖 storybook Where does a helium balloon go when you let it go? airpressurefloatingsky Discover

📖 storybook How does the AC make cold air? heathomemachinesenergy Discover