★More than half of all people alive today have never made a phone call.★Hot water freezes faster than cold water. This is called the Mpemba effect.★29th May is officially Put a Pillow on Your Fridge Day.★Cows have regional accents, they moo differently in different areas.★Bananas are berries, but strawberries are not.★Most 'silver' spoons are actually made of stainless steel.★Rats laugh when tickled.★There are only two countries in the world whose names start with 'The': The Gambia and The Bahamas.★It is physically impossible to hum while holding your nose.★The French language has 13 different words for 'kiss'.★A hummingbird's heart can beat up to 1,260 times per minute.★Scotland's national animal is the unicorn.★Humans are the only animals that blush.★The Mona Lisa has no eyebrows or eyelashes.★The fear of long words is ironically called hippopotomonstrosesquippedaliophobia.★There are more possible iterations of a game of chess than atoms in the observable universe.★The smell of freshly cut grass is actually a plant distress signal.★There is a village in Norway called 'Hell' that freezes over every winter.★The Hawaiian alphabet has only 13 letters.★The oldest 'your mom' joke was discovered on a 3,500 year old Babylonian tablet.★Cleopatra lived closer in time to the Moon landing than to the building of the Great Pyramid.★The dot over the letter 'i' is called a tittle.★Your tongue print is as unique as your fingerprint.★Polar bears have black skin under their white fur.★Octopuses can taste with their arms.★Sloths can hold their breath longer than dolphins can.★Cherophobia is an irrational fear of fun or happiness.★Sea cucumbers breathe through their butts.★Ancient Egyptians slept on stone pillows.★A blue whale's heart is roughly the size of a small car.★A crocodile can't stick its tongue out.★Humans blink about 15 to 20 times per minute.★A group of porcupines is called a prickle.★Cotton candy was co-invented by a dentist.★Humans share 60% of their DNA with bananas.★Hippos can't actually swim, they walk along the riverbed.★Sea otters hold hands while sleeping so they don't drift apart.★The shortest war in history lasted 38 to 45 minutes between Britain and Zanzibar.★Starfish can regenerate their lost limbs.★An octopus has nine brains.★The 'new car smell' is made of dozens of chemicals off-gassing from the interior.★Nintendo was founded in 1889 as a playing card company.★A group of pandas is called an embarrassment.★Barbie's full name is Barbara Millicent Roberts.★A group of crows mobbing a predator is literally called a 'murder patrol'.★Your stomach gets a new lining every 3 to 4 days, otherwise it would digest itself.★A newborn panda is smaller than a mouse.★Bananas are curved because they grow towards the sun.★A group of jellyfish is called a smack.★A group of ferrets is called a business.★Horses physically cannot vomit.★Pigs can't look up at the sky without rolling over.★A lion's roar can be heard from up to 5 miles away.★There's a species of jellyfish that is immortal.★A day on Venus is longer than a year on Venus.★The moon has moonquakes.★A bolt of lightning is five times hotter than the surface of the sun.★There are more than 1,000 chemicals in a cup of coffee.★A jiffy is an actual unit of time: 1/100th of a second.★Butterflies taste with their feet.★A day on Jupiter lasts only about 10 hours.★You can hear a blue whale's heartbeat from more than two miles away.★The average person walks the equivalent of three times around the world in a lifetime.★The human brain uses about 20% of the body's total energy.★A newborn kangaroo is about the size of a jellybean.★Pteronophobia is the fear of being tickled by feathers.★A group of owls is called a parliament.★7% of American adults believe that chocolate milk comes from brown cows.★Banging your head against a wall for one hour burns 150 calories.★A group of flamingos is called a 'flamboyance'.★A day on Mercury lasts 59 Earth days.★A blue whale's tongue can weigh as much as an elephant.★Antarctica is the only continent without native reptiles or snakes.★The microwave oven was invented by accident when a researcher noticed a chocolate bar melted in his pocket.★Snakes can help predict earthquakes.★Goldfish can recognize human faces.★It takes about eight minutes for sunlight to reach Earth.★Chewing gum while you chop onions helps keep you from crying.★A snail can have up to 25,000 teeth on its tongue.★The smell of rain has a name: petrichor.★Ostriches can run faster than horses.★Elephants are the only mammals that can't jump.★In Switzerland it is illegal to own just one guinea pig.★Cashews grow on the outside of a fruit, not inside a shell.★Dolphins have names for each other.★The first item ever sold on eBay was a broken laser pointer.★Cows have best friends and get stressed when separated.★Dolphins sleep with one eye open.★Avocados are toxic to most animals except humans.★A mosquito has 47 teeth.★The longest hiccuping spree lasted 68 years.★If you lift a kangaroo's tail off the ground it can't hop.★The average person spends six months of their life waiting for red lights to turn green.★So far, two diseases have successfully been eradicated: smallpox and rinderpest.★A group of frogs is called an army.★A rhinoceros' horn is made of keratin, the same stuff as hair.★The inventor of the Pringles can is buried in one.★Sloths only poop about once a week.★Cats can't taste sweetness.★A 'jiffy' is one trillionth of a second in physics.★A 'moment' was medieval unit of time equal to 90 seconds.★Pigeons can recognize themselves in a mirror.★Google processes more than 8.5 billion searches every single day.★Pineapples take about two years to grow.★Octopuses have three hearts and blue blood.★We have mapped more of Mars than of our own ocean floor.★The world's oldest known recipe is for beer.★Sharks existed on Earth before trees did.★Your nose can remember 50,000 different scents.★A snail can sleep for three years straight.★The Eiffel Tower can grow up to 6 inches taller during summer.★Bubble wrap was originally invented as wallpaper.★Voice actors for Mickey and Minnie Mouse got married in real life.★Koalas have fingerprints nearly identical to humans.★Wombat poop is cube-shaped.★The shortest commercial flight in the world lasts just 57 seconds.★Ketchup was once sold as medicine in the 1830s.★Bees can recognize individual human faces.★The first computer mouse was made of wood.★There are more stars in the universe than grains of sand on every beach on Earth.★Saturn would float if you could find an ocean big enough.★Vincent van Gogh only sold one painting during his lifetime.★The longest recorded flight of a chicken lasted 13 seconds.★A shrimp's heart is located in its head.★A cloud can weigh more than a million pounds.★A hippo's sweat is pink.★A flock of crows is known as a murder.★The Great Wall of China is not visible from space with the naked eye.★The Statue of Liberty was originally intended to be a lighthouse.★Peanuts aren't nuts, they are legumes.★Tigers have striped skin, not just striped fur.★Dragonflies have been around for about 300 million years.★Crows can recognize human faces and hold grudges for years.★The Dutch were once the tallest people in the world.★The first oranges weren't orange, they were green.★Honey never spoils. Archaeologists found 3000-year-old honey in Egyptian tombs that was still edible.

★More than half of all people alive today have never made a phone call.★Hot water freezes faster than cold water. This is called the Mpemba effect.★29th May is officially Put a Pillow on Your Fridge Day.★Cows have regional accents, they moo differently in different areas.★Bananas are berries, but strawberries are not.★Most 'silver' spoons are actually made of stainless steel.★Rats laugh when tickled.★There are only two countries in the world whose names start with 'The': The Gambia and The Bahamas.★It is physically impossible to hum while holding your nose.★The French language has 13 different words for 'kiss'.★A hummingbird's heart can beat up to 1,260 times per minute.★Scotland's national animal is the unicorn.★Humans are the only animals that blush.★The Mona Lisa has no eyebrows or eyelashes.★The fear of long words is ironically called hippopotomonstrosesquippedaliophobia.★There are more possible iterations of a game of chess than atoms in the observable universe.★The smell of freshly cut grass is actually a plant distress signal.★There is a village in Norway called 'Hell' that freezes over every winter.★The Hawaiian alphabet has only 13 letters.★The oldest 'your mom' joke was discovered on a 3,500 year old Babylonian tablet.★Cleopatra lived closer in time to the Moon landing than to the building of the Great Pyramid.★The dot over the letter 'i' is called a tittle.★Your tongue print is as unique as your fingerprint.★Polar bears have black skin under their white fur.★Octopuses can taste with their arms.★Sloths can hold their breath longer than dolphins can.★Cherophobia is an irrational fear of fun or happiness.★Sea cucumbers breathe through their butts.★Ancient Egyptians slept on stone pillows.★A blue whale's heart is roughly the size of a small car.★A crocodile can't stick its tongue out.★Humans blink about 15 to 20 times per minute.★A group of porcupines is called a prickle.★Cotton candy was co-invented by a dentist.★Humans share 60% of their DNA with bananas.★Hippos can't actually swim, they walk along the riverbed.★Sea otters hold hands while sleeping so they don't drift apart.★The shortest war in history lasted 38 to 45 minutes between Britain and Zanzibar.★Starfish can regenerate their lost limbs.★An octopus has nine brains.★The 'new car smell' is made of dozens of chemicals off-gassing from the interior.★Nintendo was founded in 1889 as a playing card company.★A group of pandas is called an embarrassment.★Barbie's full name is Barbara Millicent Roberts.★A group of crows mobbing a predator is literally called a 'murder patrol'.★Your stomach gets a new lining every 3 to 4 days, otherwise it would digest itself.★A newborn panda is smaller than a mouse.★Bananas are curved because they grow towards the sun.★A group of jellyfish is called a smack.★A group of ferrets is called a business.★Horses physically cannot vomit.★Pigs can't look up at the sky without rolling over.★A lion's roar can be heard from up to 5 miles away.★There's a species of jellyfish that is immortal.★A day on Venus is longer than a year on Venus.★The moon has moonquakes.★A bolt of lightning is five times hotter than the surface of the sun.★There are more than 1,000 chemicals in a cup of coffee.★A jiffy is an actual unit of time: 1/100th of a second.★Butterflies taste with their feet.★A day on Jupiter lasts only about 10 hours.★You can hear a blue whale's heartbeat from more than two miles away.★The average person walks the equivalent of three times around the world in a lifetime.★The human brain uses about 20% of the body's total energy.★A newborn kangaroo is about the size of a jellybean.★Pteronophobia is the fear of being tickled by feathers.★A group of owls is called a parliament.★7% of American adults believe that chocolate milk comes from brown cows.★Banging your head against a wall for one hour burns 150 calories.★A group of flamingos is called a 'flamboyance'.★A day on Mercury lasts 59 Earth days.★A blue whale's tongue can weigh as much as an elephant.★Antarctica is the only continent without native reptiles or snakes.★The microwave oven was invented by accident when a researcher noticed a chocolate bar melted in his pocket.★Snakes can help predict earthquakes.★Goldfish can recognize human faces.★It takes about eight minutes for sunlight to reach Earth.★Chewing gum while you chop onions helps keep you from crying.★A snail can have up to 25,000 teeth on its tongue.★The smell of rain has a name: petrichor.★Ostriches can run faster than horses.★Elephants are the only mammals that can't jump.★In Switzerland it is illegal to own just one guinea pig.★Cashews grow on the outside of a fruit, not inside a shell.★Dolphins have names for each other.★The first item ever sold on eBay was a broken laser pointer.★Cows have best friends and get stressed when separated.★Dolphins sleep with one eye open.★Avocados are toxic to most animals except humans.★A mosquito has 47 teeth.★The longest hiccuping spree lasted 68 years.★If you lift a kangaroo's tail off the ground it can't hop.★The average person spends six months of their life waiting for red lights to turn green.★So far, two diseases have successfully been eradicated: smallpox and rinderpest.★A group of frogs is called an army.★A rhinoceros' horn is made of keratin, the same stuff as hair.★The inventor of the Pringles can is buried in one.★Sloths only poop about once a week.★Cats can't taste sweetness.★A 'jiffy' is one trillionth of a second in physics.★A 'moment' was medieval unit of time equal to 90 seconds.★Pigeons can recognize themselves in a mirror.★Google processes more than 8.5 billion searches every single day.★Pineapples take about two years to grow.★Octopuses have three hearts and blue blood.★We have mapped more of Mars than of our own ocean floor.★The world's oldest known recipe is for beer.★Sharks existed on Earth before trees did.★Your nose can remember 50,000 different scents.★A snail can sleep for three years straight.★The Eiffel Tower can grow up to 6 inches taller during summer.★Bubble wrap was originally invented as wallpaper.★Voice actors for Mickey and Minnie Mouse got married in real life.★Koalas have fingerprints nearly identical to humans.★Wombat poop is cube-shaped.★The shortest commercial flight in the world lasts just 57 seconds.★Ketchup was once sold as medicine in the 1830s.★Bees can recognize individual human faces.★The first computer mouse was made of wood.★There are more stars in the universe than grains of sand on every beach on Earth.★Saturn would float if you could find an ocean big enough.★Vincent van Gogh only sold one painting during his lifetime.★The longest recorded flight of a chicken lasted 13 seconds.★A shrimp's heart is located in its head.★A cloud can weigh more than a million pounds.★A hippo's sweat is pink.★A flock of crows is known as a murder.★The Great Wall of China is not visible from space with the naked eye.★The Statue of Liberty was originally intended to be a lighthouse.★Peanuts aren't nuts, they are legumes.★Tigers have striped skin, not just striped fur.★Dragonflies have been around for about 300 million years.★Crows can recognize human faces and hold grudges for years.★The Dutch were once the tallest people in the world.★The first oranges weren't orange, they were green.★Honey never spoils. Archaeologists found 3000-year-old honey in Egyptian tombs that was still edible.

Lights out

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How to play Lights out

All cells in the 5 by 5 grid start as a mix of lit and dark squares. Tap a cell to toggle it and its four neighbours: up, down, left and right. Edge cells toggle fewer neighbours. Your goal is to turn off every single light. The game tracks how many taps you used. There is no time pressure, just see how few moves you need to clear the board.

Tips

Solve row by row from top to bottom, do not jump around
After fixing the top four rows, the bottom row tells you the rest
Plan two or three moves ahead, lights out punishes guessing
If you get stuck, restart, the same puzzle has many paths to the solution

About Lights out

Lights Out was a handheld toy released by Tiger Electronics in 1995 with a glowing red LED grid. The puzzle is older than the toy. Mathematicians had been studying similar parity puzzles for decades. Every starting board has a known shortest solution that pure logic can reach. The fun part is finding it without writing equations. Our digital version gives you fresh layouts and an undo button so you can experiment without restarting.

More logic games

2048: Slide tiles to combine them. Reach 2048 or beyond.
Memory: Find every matching pair. Easy on the brain, hard to put down.
Sudoku mini: A quick 6x6 sudoku you can finish on a coffee break.
Drop four: Stack four discs in a row. Beat the friendly bot.
Reversi: Flip your way to a bigger army. Othello against an AI.
Slide fifteen: The classic 15 puzzle. Slide tiles into order in as few moves as possible.

Browse the full arcade →

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