1. You Only Use 10% of Your Brain
For years, teachers and even textbooks repeated the idea that humans only use about 10% of their brains. It sounded scientific enough to stick, and plenty of movies have run with the myth to this day. But in reality, brain scans show activity throughout the entire brain, even when we’re resting. Different regions handle everything from memory to movement, so the idea of vast unused brain power just isn’t true.
The appeal of the myth is easy to understand—it makes us feel like we have hidden superpowers waiting to be unlocked. Teachers may have used it as motivation, but it’s misleading. While we do have untapped potential in terms of learning, our brains are very much working at full capacity already.
2. Swallowed Gum Stays in Your Stomach for 7 Years
Most of us remember being warned never to swallow gum because it would stay in our stomach for seven years. It made recess a little scarier when you accidentally swallowed your bubblegum. But the truth is gum is indigestible, so it just passes through your system like other fiber.
The myth was probably spread by adults who wanted to discourage kids from swallowing something that isn’t exactly food. While swallowing gum isn’t a good habit, it doesn’t stick to your insides for years on end. Your body has its own way of keeping things moving along.
3. Chameleons Change Color to Camouflage
Teachers loved pointing to chameleons as nature’s camouflage experts, able to blend in perfectly with their surroundings. While it’s true their skin changes color, the main reason isn’t camouflage—it’s communication and temperature regulation. Their skin cells shift pigments to signal moods or adjust to the heat.
The idea that they vanish into any background is a fun exaggeration that has fueled cartoons and children’s books. In reality, if a chameleon is sitting on a red chair, it’s not about to turn bright red. It might shift shades to show it’s stressed, but blending into wallpaper isn’t happening.
4. Goldfish Have a Three-Second Memory
One of the most repeated classroom “facts” was that goldfish forget everything in a matter of seconds. Kids used it as proof that their pet fish lived in a constant fog. But studies have shown goldfish can remember things for months, including feeding schedules and learned behaviors.
This myth probably started because we underestimate animals that don’t express themselves like dogs or cats. Teachers may have thought it was a harmless way to teach kids about memory, but it paints goldfish unfairly. Your little orange friend actually knows you better than you think.
5. The Tongue Has Four Taste Zones
Remember the diagrams showing the tongue divided into neat zones—sweet at the tip, salty on the sides, bitter at the back, and sour in between? Teachers often drew it on the chalkboard as if it were fact. But modern science has debunked it. All taste buds can detect all flavors, though sensitivity varies slightly.
The myth comes from a mistranslation of an old German study that showed tiny differences in sensitivity. Over time, it turned into the “taste map” we all saw in school. So, the next time you’re enjoying chocolate, your entire tongue is involved, not just the tip.
6. Columbus Proved the Earth Was Round
Many classrooms taught that Christopher Columbus bravely set sail to prove the Earth wasn’t flat. It’s a heroic tale, but not historically accurate. Educated Europeans had known the Earth was round since ancient Greece. Columbus was actually trying to find a faster route to Asia.
Teachers leaned on the story because it made for a neat narrative about courage and discovery. The reality is more complicated—and less flattering—since his voyages led to colonization and exploitation. Still, the “flat Earth vs. Columbus” myth remains stubborn in school lessons.
7. Sugar Makes Kids Hyper
It’s practically a staple in classrooms and birthday parties—teachers and parents alike warned that too much sugar would turn kids into wild animals. But scientific studies have consistently found no link between sugar consumption and hyperactivity. What kids often respond to is the excitement of the environment, not the cake.
The myth was probably reinforced by observation bias. When kids had sugar at a party, adults noticed the energy spike and blamed the sweets. But the truth is, kids can run circles around us with or without frosting.
8. Humans Only Have Five Senses
Teachers drilled into us the classic five senses: sight, sound, taste, touch, and smell. While that’s not wrong, it’s not the whole picture. Humans actually have many more senses, including balance (vestibular), temperature (thermoception), and even the awareness of where our body is in space (proprioception).
The “five senses” idea came from Aristotle and stuck because it was simple and easy to teach. But in reality, your body is tuned into a whole world of sensations you probably don’t even notice. Teachers weren’t lying so much as oversimplifying.
9. Cracking Your Knuckles Causes Arthritis
How many times did teachers or even grandparents scold you for cracking your knuckles, warning you’d regret it with arthritis later? It turns out, research has found no direct link between the habit and arthritis. The popping sound is just gas bubbles collapsing in your joints.
This myth stuck around because it sounded logical—why wouldn’t stressing your joints cause problems? While cracking might annoy people around you, it’s not setting you up for a lifetime of joint pain. Teachers may have just wanted a reason to stop the distracting noise.
10. The Great Wall of China Is Visible from Space
It’s a favorite geography class nugget: the Great Wall of China is the only manmade structure you can see from space. But astronauts have confirmed this isn’t true. The wall is long, but it’s narrow and blends into the landscape. From orbit, cities and roads are much more noticeable than the wall.
The myth likely took root because the Great Wall is so iconic and massive on the ground. Teachers wanted a dramatic way to show its scale. But outer space doesn’t play favorites—it’s not nearly as visible as people were led to believe.
11. Carrots Improve Your Night Vision
Plenty of teachers told us that eating carrots would give us super-powered night vision. While carrots are healthy and packed with vitamin A, which supports eye health, they won’t turn you into a nocturnal creature. The myth was actually popularized during World War II by British propaganda to explain radar technology.
Teachers may have just passed it along as nutrition advice, and it’s not entirely wrong—vitamin A deficiency can harm your vision. But munching carrots won’t have you spotting owls in the dark any better than before. It’s one of those half-true myths that just stuck.
12. Lightning Never Strikes the Same Place Twice
Teachers sometimes used this phrase metaphorically, but many students took it literally. In reality, lightning often strikes the same place multiple times, especially tall structures like skyscrapers or trees. The Empire State Building, for example, gets hit dozens of times a year.
The phrase probably lasted because it sounded comforting or dramatic. But it’s misleading, and in some cases, dangerous if people think a struck spot is suddenly safe. The truth is, lightning likes familiar targets and will revisit them again and again.
13. Bats Are Blind
“Blind as a bat” became a classroom cliché, often repeated by teachers teaching about nocturnal animals. But bats are not blind at all. Most species have perfectly good eyesight, and some even see better than humans in low light. Echolocation is just an extra tool, not a replacement for vision.
The myth stuck because echolocation seemed so extraordinary that people assumed bats didn’t need sight. Teachers simplified the story into “bats are blind,” but it sells these animals short. They’re fascinating creatures with both sharp eyes and an incredible built-in sonar system.