If you graduated in 1965…
Here’s what your teachers got wrong.

Pluto is the ninth planet in our solar system.

Pluto was reclassified as a dwarf planet by the IAU in 2006. The solar system now has 8 recognized planets.

The tongue has distinct zones for different tastes: sweet at the tip, bitter at the back, sour and salty on the sides.

All taste types can be detected across the entire tongue. The taste map was based on a misreading of a 1901 German study. A fifth basic taste, umami, also exists and was not recognized in Western curricula until much later.

Dogs see the world in black and white.

Dogs see colors, but their spectrum is limited compared to humans. They see shades of blue and yellow but cannot distinguish red and green.

Goldfish have a memory of only 3 seconds.

Goldfish can remember things for months, recognize their owners, and learn complex tasks.

Your hair and fingernails continue to grow after you die.

Hair and nails do not grow after death. The skin around them retracts due to dehydration, creating the illusion of growth.

Humans evolved from monkeys or apes.

Humans and modern apes share a common ancestor. We did not evolve from any living ape species. The common ancestor lived 6-8 million years ago.

Neanderthals were primitive, brutish, and less intelligent than modern humans.

Neanderthals had larger brains than modern humans, made sophisticated tools, created art, buried their dead, and interbred with Homo sapiens. Most non-African humans carry 1-4% Neanderthal DNA.

Animals act purely on instinct and do not experience emotions, form memories, or engage in complex reasoning.

Decades of research in ethology and comparative psychology have documented complex emotions, long-term memory, social learning, and problem-solving across many animal species.

Male pattern baldness is inherited from your mother's side of the family.

Male pattern baldness is polygenic, involving variants from both maternal and paternal chromosomes. The androgen receptor gene on the X chromosome plays a significant role but multiple loci on autosomes also contribute.

Moss grows on the north side of trees, so you can use it as a compass if lost in the woods.

Moss grows wherever moisture and shade are sufficient. These conditions depend on local terrain, tree canopy, prevailing wind, and microclimate. Moss distribution does not reliably indicate compass direction.

The Great Wall of China is the only human-made object visible from space (or from the Moon).

The Great Wall is very difficult to see with the naked eye from low Earth orbit and is not visible from the Moon. Many structures (cities, highways, airports) are more visible.

Nuclear power is the most dangerous energy source, with the highest death toll per unit of energy.

Nuclear power has one of the lowest death tolls per unit of energy produced. Coal and oil cause far more deaths from air pollution, accidents, and climate change. Even including Chernobyl and Fukushima, nuclear is statistically safer than fossil fuels.

If one country falls to communism, its neighbors will inevitably follow - the 'domino theory.'

The domino theory oversimplified revolutionary movements as monolithic communist spread. Vietnam fell in 1975 but most predicted dominoes did not fall.

Betsy Ross designed and sewed the first American flag.

There is no contemporary evidence linking Betsy Ross to the first flag. The story was promoted by her grandson William Canby in 1870, nearly a century after the supposed event, with no documentation.

Christopher Columbus proved the Earth was round by sailing west to reach India.

The Earth's roundness was known since ancient Greece (Eratosthenes measured it ~240 BCE). Columbus miscalculated Earth's size and did not reach India.

Albert Einstein failed math in school.

Einstein excelled in mathematics from an early age. He taught himself calculus by age 12 and was doing advanced math before most students. The myth conflates a change in grading systems.

The Emancipation Proclamation freed all slaves in the United States.

The Emancipation Proclamation only freed slaves in Confederate-held territories, not in Union border states or areas already under Union control. The 13th Amendment (1865) abolished slavery nationwide.

Marie Antoinette said 'Let them eat cake' when told the French peasants had no bread.

There is no evidence Marie Antoinette ever said this. The quote was attributed to 'a great princess' by Rousseau in 1766, when she was only 10. It was likely revolutionary propaganda.

Paul Revere rode through the night shouting 'The British are coming!' to warn colonists.

Revere and other riders used discretion to avoid British patrols. Revere likely said 'the regulars are coming out.' Multiple riders participated. Revere was captured before reaching Concord.

Witches were burned at the stake during the Salem witch trials.

No one was burned at Salem. Nineteen people were hanged, one was pressed to death with stones, and several died in jail. Burning was the European punishment, not the American one.

Vikings discovered America but then vanished without leaving a lasting presence.

Norse explorers established a settlement at L'Anse aux Meadows in Newfoundland around 1000 CE. Evidence suggests further exploration southward. They did not 'vanish' - the settlement was abandoned, likely due to conflict with Indigenous peoples and limited resources.

George Washington's dentures were carved from wood.

Washington's dentures were constructed from combinations of human teeth, animal teeth (cow, horse), hippopotamus ivory, elephant ivory, and lead alloy. No wood was used. The myth likely arose from the staining and darkening of ivory.

0.999... (repeating nines) approaches 1 but never actually equals 1.

0.999... is exactly equal to 1, not approximately equal. They are two representations of the same real number. Since 1/3 = 0.333..., multiplying both sides by 3 gives 0.999... = 1. More formally, the real number system defines a repeating decimal as the limit of its partial sums, and the limit of 0.9, 0.99, 0.999, ... is exactly 1.

In the Monty Hall problem, switching doors after the host reveals a goat makes no difference; you still have a 50/50 chance of winning.

Switching wins 2/3 of the time, not 1/2. The host always opens a losing door he already knows about, which preserves the contestant's original 1/3 probability on the chosen door and concentrates the remaining 2/3 on the other door. Computer simulations and mathematical proofs both confirm this, and the controversy was definitively settled by the mid-1990s.

Infinity is infinity. There is only one infinite quantity, and all infinities are the same size.

Georg Cantor proved in 1891 that there are different sizes of infinity. The set of real numbers is strictly larger than the set of counting numbers, even though both are infinite. His diagonal argument showed that no complete list of real numbers is possible, because a new real number not on any list can always be constructed.

The angles in any triangle always add up to exactly 180 degrees.

The 180-degree rule holds only in flat Euclidean space. On the surface of a sphere, a triangle with one vertex at the North Pole and two vertices on the equator 90 degrees apart has three right angles, summing to 270 degrees. Einstein's general relativity confirmed that physical space near massive objects is geometrically curved, and light-ray triangles near massive stars do not obey the Euclidean rule.

1 is a prime number.

By modern definition, 1 is not prime. Primality requires exactly two distinct positive divisors, and 1 has only one: itself. The exclusion preserves the Fundamental Theorem of Arithmetic, which states that every integer greater than 1 has a unique prime factorization. If 1 were prime, 12 could be factored as 2x2x3 or as 1x2x2x3 or 1x1x2x2x3, making factorizations non-unique.

Mathematics is a complete formal system: any true mathematical statement can eventually be proved.

Gödel's 1931 incompleteness theorems proved this impossible. Any consistent formal system powerful enough to express basic arithmetic contains true statements that cannot be proved within that system. No set of axioms can be simultaneously complete and consistent.

In random sequences, a streak of one outcome makes the opposite outcome more likely; the 'law of averages' must balance things out.

Independent random events have no memory. A fair coin's probability of landing heads is exactly 50% regardless of any preceding streak. The law of large numbers describes proportions converging over enormous sample sizes but makes no promise about any individual event or short sequence.

You cannot take the square root of a negative number. It is undefined and mathematically impossible.

The square root of negative one, written as i, defines the imaginary unit and extends the real numbers to the complex number system. Complex numbers are physically real in the deepest sense: quantum mechanics cannot be expressed using only real numbers, and electrical engineering, signal processing, and GPS calculations all rely on complex arithmetic.

Shaving makes hair grow back thicker, darker, or faster.

Shaving only cuts hair at the surface. It does not affect growth rate, thickness, or color. The blunt tip may feel coarser temporarily.

Stomach ulcers are caused by stress and spicy food.

Most peptic ulcers are caused by H. pylori bacterial infection or NSAIDs. Established by Marshall and Warren in 1982–1984.

Antibiotics can cure colds and flu.

Antibiotics target bacteria, not viruses. Colds and flu are caused by viruses. Taking antibiotics for viral infections contributes to antibiotic resistance without helping the patient.

Normal human body temperature is exactly 98.6°F (37°C).

Body temperature varies by person, time of day, and measurement method. A 2020 study found the average is closer to 97.5°F (36.4°C) and has been declining slightly over time.

Margarine is healthier than butter because it is lower in saturated fat.

Early margarines contained trans fats, which are more harmful than the saturated fat in butter. Modern margarines have improved but are still highly processed. Butter in moderation is now considered acceptable by many nutritionists.

Eating carrots improves your night vision significantly.

Vitamin A deficiency can impair night vision, but eating extra carrots beyond normal dietary levels does not enhance vision in people who are not deficient. The myth was WWII propaganda to hide radar technology.

Detox diets, cleanses, and specific foods can remove toxins from your body.

The liver, kidneys, lungs, and skin already detoxify the body effectively. There is no scientific evidence that detox diets, cleanses, or supplements remove toxins better than these organs do.

Drinking red wine is good for your heart due to resveratrol and antioxidants.

The evidence for red wine's heart benefits is weak and confounded by lifestyle factors. The 'French Paradox' was largely based on flawed data. Any potential benefits are outweighed by the known harms of alcohol.

Eating too much sugar causes Type 2 diabetes.

Type 2 diabetes is caused by a combination of genetic factors, insulin resistance, and overall metabolic health. While excessive sugar consumption contributes to obesity (a risk factor), sugar itself does not directly cause diabetes. Type 1 diabetes is an autoimmune condition unrelated to diet.

Giving children sugar makes them hyperactive.

Controlled studies show no consistent causal link between sugar and hyperactivity. Parental expectations likely explain the perceived effect.

Dinosaurs were cold-blooded like modern reptiles.

Many dinosaurs were warm-blooded (endothermic) or had intermediate metabolisms. Evidence includes bone structure, growth rates, and the discovery of feathered dinosaurs in cold climates.

Brontosaurus was a distinct long-necked dinosaur species, one of the largest land animals ever.

Brontosaurus was reclassified as Apatosaurus in 1903, though the name was briefly reinstated as a separate genus in 2015. As of 2015, it may be distinct again.

Pterodactyls and pterosaurs were dinosaurs.

Pterosaurs were flying reptiles, not dinosaurs. Dinosaurs belong to the clade Dinosauria; pterosaurs belong to Pterosauria. They are close relatives but distinct groups.

T-Rex arms were tiny and useless.

T-Rex arms were surprisingly strong and muscular. They may have been used for grasping prey, mating, or helping the animal rise from a prone position.

Velociraptors were human-sized, highly intelligent predators.

Velociraptors were turkey-sized, about 2 feet tall. Jurassic Park used Deinonychus as the model but called them Velociraptors because the name sounded better.

Centrifugal force is a real outward force that pushes objects away from the center of rotation.

Centrifugal force is a fictitious (inertial) force - it only appears in rotating reference frames. The real force is centripetal, pulling inward.

Lightning never strikes the same place twice.

Lightning frequently strikes the same place multiple times. Tall structures like the Empire State Building are struck dozens of times per year.

There are three states of matter: solid, liquid, and gas.

There are at least four fundamental states (solid, liquid, gas, plasma), plus many others like Bose-Einstein condensates, superfluids, and more.

Homosexuality is a psychological disorder requiring treatment.

Homosexuality is a normal variation of human sexuality. The APA removed it from the DSM in 1973. Conversion therapy has since been shown to cause harm with no demonstrated benefit.

Humans only use 10% of their brain.

Virtually all brain regions have identified functions and show activity throughout the day. The 10% figure has no basis in neuroscience.

Some people have photographic memory and can recall images with perfect accuracy.

True eidetic memory (photographic recall) has never been reliably demonstrated in adults. Hyperthymesia (highly superior autobiographical memory) is real but extremely rare. Most 'photographic memory' claims are explainable by trained mnemonic techniques.

We only remember 10% of what we read and 20% of what we hear - known as 'Dale's Cone of Experience.'

Dale's Cone was originally about instructional media, not retention percentages. The specific percentages were added later by anonymous sources and have no scientific basis.

Women are naturally worse at math and spatial reasoning than men due to biological differences.

No consistent biological evidence supports innate sex differences in mathematical ability. Performance gaps are largely explained by stereotype threat, educational access, and cultural expectations.

Lead in paint and gasoline is safe and poses no health risk.

Lead is a potent neurotoxin, especially harmful to children's brain development. Leaded gasoline was phased out starting in the 1970s, and lead paint was banned in 1978 in the US.

Drinking alcohol warms you up in cold weather.

Alcohol causes blood vessels to dilate, creating a warm feeling on the skin but actually increasing heat loss from the core body. It increases hypothermia risk.