30 facts you were taught in school that aren't actually true anymore

Though Pluto had been recognized as the ninth and smallest planet in our solar system for decades, its status was downgraded to a dwarf planet in 2006. The discovery of other Kuiper Belt Objects that are roughly the same size as Pluto led to its change in status.

Oral hygiene and dentistry weren't exactly stellar in the 18th century, so it makes sense that George Washington and many of his contemporaries had false teeth. However, the first president's teeth weren't actually made of wood, as many students learn, but of lead, human teeth, cow teeth, and ivory.  

Napoleon's reputation as a runt is mostly a myth. Historians now put him at between 5'5" and 5'7", average or above-average for a Frenchman of his era. Part of the confusion: the French "foot" was a different length than the British one, so his recorded height of 5'2" in French units translates to roughly 5'7" in British and American measurements. The "short" image was reinforced by British wartime propaganda cartoons mocking him, and by the fact that he was often surrounded by his unusually tall Imperial Guard.

Christopher Columbus may have a holiday named after him, but he didn't actually discover America. Though the explorer did land on several islands in what is now the Bahamas, he never actually set foot on the North American continent.

As for his ships: while Columbus did sail on the Niña, Pinta, and Santa Maria, those weren't their actual names. The Niña was likely named Santa Clara, the Pinta's original name is unknown, and the Santa Maria was also called La Gallega—Spanish ships were traditionally named after saints but called by nicknames.

Sir Isaac Newton still can be credited with discovering gravity, but he didn't get his bright idea after being smacked in the head by a falling apple. His brain wave actually occurred after watching an apple fall from a tree.

The German-born physicist was certainly eccentric, but that didn't make him a bad student. Though teachers might like to tell students that Einstein wasn't always good at math to encourage them, he was actually always successful in school.

Almost every detail that students are taught about the origin of Thanksgiving is false. No turkey or pumpkin pie was served, the Pilgrims didn't invite the Native Americans to their table, and they didn't celebrate Thanksgiving on the fourth Thursday in November.

The Great Wall is not visible to the naked eye from orbit. Astronauts from the Apollo missions through the International Space Station, including China's own first astronaut, Yang Liwei, have confirmed you can't pick it out without magnification, because it's too narrow and follows the natural color and contour of the land. The myth predates spaceflight entirely: it traces back to a 1932 Ripley's Believe It or Not cartoon. With cameras and zoom lenses, plenty of large human-made structures are photographable from orbit, including big bridges, airports, and cities.

The cartoon depiction of the raindrop looks a lot like a tear, but scientists say this isn't accurate. Most falling raindrops actually look flat—more like hamburger buns—according to the United States Geological Survey.

Despite what your English teacher may have said, you can actually start a sentence with a conjunction. Grammar purists won't be happy about it, but who cares?

Possibly confused by the fact that some of your veins appear blue, many schoolchildren believe that blood only turns red when it's exposed to oxygen. However, this just isn't true.

Odds are, some resourceful parent or teacher decided to make up this untruth to stop kids from swallowing gum. Though chewing gum isn't as easily digested as other foods, it won't remain in your body for any length of time.

July 4, 1776, is the date the Continental Congress formally adopted the text of the Declaration of Independence, two days after delegates had voted for independence itself, on July 2. New York's delegation abstained because it lacked authorization to support independence; New York's Provincial Congress granted that authorization on July 9, making approval among the colonies unanimous.

The famous engrossed copy most people picture was signed by most delegates on August 2, 1776, with several signatures added later. Although the United States governed itself and gained recognition from countries such as France during the Revolutionary War, Britain did not formally recognize American independence until the Treaty of Paris in 1783.

Diamond is no longer the definitive record holder. In 2005, researchers at the University of Bayreuth synthesized aggregated diamond nanorods (sometimes called hyperdiamond) by compressing buckminsterfullerene (C60) under extreme pressure. In lab testing, the material scratched the hardest natural diamond faces, meaning it's harder than diamond by direct measurement, not just theory.

Separately, a 2009 study proposed that wurtzite boron nitride and a rare natural form of carbon called lonsdaleite might be harder still, based on computer simulations, but those predictions haven't been confirmed through direct testing: both are so rare that scientists have never had a large enough sample to measure.

Biology classes typically include a lesson on the classification of life. Many children learned that there are five classifications—animals, plants, bacteria, fungi, and protists—but scientists now believe that there are as many as eight.

There is a nugget of truth to this idea: About 90 percent of brain cells are white matter and are never used for thinking. However, all parts of the human brain are in use at all times—just not specifically for thought.

These reptiles do frequently change colors, but they don't use these special abilities to camouflage themselves. Instead, chameleons use different colors to communicate with each other and control their body temperature.  

Teachers thought they were absolutely correct when they taught students that Earth was the only planet to contain water. However, NASA discoveries have revealed water exists elsewhere in our solar system. In 2015, NASA found evidence suggesting seasonal liquid water flows on Mars' surface, though this remains debated. More recently, in 2024, researchers analyzing data from NASA's InSight lander discovered evidence of a large underground reservoir of liquid water deep within Mars' crust, located 7-13 miles below the surface.

No one is claiming that goldfish are particularly bright, but they at least deserve a little bit more credit than most people give them. Scientific studies have demonstrated that fish possess much longer memories than the three-second myth suggests. Research on African cichlids showed memory retention for at least 12 days, while studies on goldfish specifically have found they can remember information for months and can be trained to recognize patterns and locations.

Saying that the United States is a democracy might be oversimplifying our government. In fact, the founders established the country as a republic that combined elements of monarchy, aristocracy, and democracy.

During the mass hysteria about witchcraft culminating in the Salem Witch Trials, witches were sentenced to death. However, they weren't actually burned—instead, most were hanged.

An article written in the 1970s speculated that the Salem Witch Trials were actually triggered by ergot poisoning. Ergot—a fungus that can grow on rye in wet conditions—very possibly made its way into early settlers' bread, but its hallucinogenic properties were likely not strong enough to cause such mass hysteria.

Despite the popular image of Pilgrims wearing all black and white with a wide-brimmed hat and buckled shoes, this stereotype isn't true. Black and white outfits were typically reserved for Sundays and special occasions, while men and women wore all kinds of colors during the week.

Children who grew up between the 1970s and 90s likely remember the food pyramid, a visual aid that taught students to eat mostly carbs, then vegetables and fruit, then meat and dairy products. Since then, the United States Department of Agriculture has totally overhauled its nutrition program to promote a more balanced diet of whole grains, fruit, vegetables, and protein. In 2026, however, the U.S.D.A. and the U.S. Department of Health and Human Services introduced a controversial new "inverted food pyramid" spearheaded by Health Secretary Robert F. Kennedy, Jr.

Many pimply teenagers probably remember a health teacher instructing them to lay off the chocolate to clear up their skin. While there is some evidence that sugar can exacerbate acne, most doctors agree that chocolate itself can't cause breakouts.

Here's another common lesson that teachers likely used to make their lives easier: You can safely eat anything that drops on the floor as long as it didn't rest there for longer than five seconds. In reality, however, it only takes a fraction of a second for bacteria to contaminate a piece of food.

Though parents still probably don't like the idea of their kids drinking coffee at a young age, they'll have to find another rationale to stop them. There is no evidence that caffeine can have significant impacts on physical growth.

In 1974, Dr. William Cook wrote a letter to the American Academy of Pediatrics detailing his belief that sugar causes hyperactivity in children. The idea took off from there, though studies have failed to find any link between the two.

Dogs do see colors differently than humans, but they're not actually colorblind. In fact, canines can see blues and greens, and have better vision in low light than humans.

Teachers often used this fun fact to teach physics principles like velocity. However, the math just doesn't add up: At most, a penny falling from the top of the Empire State Building would hurt you quite a bit.