Challenge Your Brain With 30 ‘True Or False’ Questions You Probably Didn’t Know

I’ve always been fascinated by the simple, almost primal appeal of a good true or false questions challenge. It’s a format so deeply ingrained in us, from those pop quizzes in school to the playful debates that spring up around a dinner table with friends. There’s something uniquely compelling about being presented with a statement of fact, or something that purports to be one, and having to tap into your reservoir of knowledge, logic, and sometimes pure instinct to declare it as truth or fiction. It’s a mental workout that feels more like a game, a quick spark that can ignite curiosity and lead you down rabbit holes of information you never knew existed. The beauty lies not just in getting the answer right, but in the surprising journey of discovering why something you always assumed was correct is, in fact, completely backward. This collection is designed to do exactly that—to challenge your assumptions and introduce you to some of the more obscure, counterintuitive, and wonderfully strange corners of general knowledge. So, find a comfortable spot, clear your mind, and let’s put your brain to the test with thirty of these intriguing puzzles. Let’s start with a classic misconception that many people accept without a second thought.

You have probably heard the claim that we only use ten percent of our brains, a notion that has been popularized by movies and self-help gurus promising untapped potential. This statement is, in fact, completely false. Modern neurology and brain imaging technology like fMRI and PET scans have conclusively shown that virtually every part of the brain has a function and is active almost all the time, even when we are asleep. Different tasks may engage different neural networks with varying intensity, but there is no vast, silent reservoir of gray matter waiting to be unlocked. Damage to even a small area of the brain can have devastating and specific consequences, which simply wouldn’t be the case if ninety percent of it were dormant. This myth likely persists because it’s an appealing concept, suggesting that we all have a hidden genius within us, but the scientific reality is that we are already using our brains to their full, remarkable capacity.

Let’s travel from the human mind to the animal kingdom with another common belief. The idea that a duck’s quack doesn’t echo is one of those quirky facts that gets passed around as undeniable truth. This is another false statement, and it’s surprisingly easy to debunk with a bit of basic physics. Any sound wave produced in an environment with reflective surfaces can create an echo, and a duck’s quack is no different from any other sound in that regard. The myth likely originated because a duck’s quack is often a fading, dissipating sound that doesn’t have the sharp, clear finish that makes an echo obvious to the human ear, and the acoustics of a duck’s typical open-air habitat aren’t ideal for producing a distinct, audible echo. Scientists have actually tested this in echo-friendly environments and confirmed that a duck’s quack does, indeed, echo just like any other sound. It’s a fun piece of trivia, but it doesn’t hold up to scrutiny.

Sticking with animals, let’s consider the chameleon. Most of us picture this lizard as a master of disguise, changing its skin color to blend seamlessly into any background, whether it’s a green leaf or a multicolored rug. While chameleons can and do change color, the primary reason is not for camouflage. This common understanding is mostly false. The color shifts are primarily used for communication, signaling to other chameleons during social interactions, expressing aggression, territoriality, and the desire to mate. Their skin also changes in response to temperature and light; a cold chameleon might turn dark to absorb more heat from the sun. While camouflage can be a secondary benefit in certain situations, it is far from the main event in their spectacular color-changing show. This revelation adds a whole new layer of drama to the life of a chameleon, transforming them from shy hiders into expressive communicators.

Now, let’s look upward to the sky. A great many people believe that the Great Wall of China is the only human-made structure visible from space with the naked eye. This is a resounding falsehood that has been repeated for generations. Astronauts who have spent time in low Earth orbit, from where they can see vast swathes of our planet, consistently report that the Wall is not readily visible without aid. It is simply too narrow and its colors too similar to the natural surroundings to be distinguished from such a distance. What are visible from space are large cities, which appear as sprawling gray blotches, major agricultural patterns, and even the lights of human civilization at night. The myth is a testament to the Wall’s immense cultural power, but it doesn’t align with the visual reality experienced by those who have actually been there.

Here’s a historical tidbit that often surprises people. We have this image of medieval Europeans believing the Earth was flat, only to be enlightened by courageous explorers like Columbus. This is a dramatic oversimplification that is, for the most part, false. Educated Europeans, particularly scholars and clerics since the time of the ancient Greeks, had known the Earth was spherical. Eratosthenes calculated its circumference with remarkable accuracy in the third century BC. The debate in Columbus’s time was not about whether the Earth was round, but about its size; Columbus famously and incorrectly believed it was much smaller, which is why he thought he could reach Asia by sailing west. The myth of the flat Earth was largely invented and promoted in the 19th century by writers like Washington Irving to make the past seem more primitive and the Age of Exploration seem more revolutionary. The reality is that human curiosity and intellect had figured out the shape of our world centuries before.

Let’s turn to a more tactile sensation. The notion that hair and fingernails continue to grow for a short time after a person has died is a deeply unsettling one that has found its way into countless stories and films. However, this creepy concept is biologically false. What actually happens is that the body rapidly dehydrates after death, causing the skin around the hair follicles and nail beds to retract and shrink. This retraction creates the visual illusion that the hair and nails have grown longer when, in fact, it is the surrounding tissue that has pulled back. Growth requires a complex biological process involving cell division and hormonal regulation, all of which cease abruptly when the heart stops beating and oxygenated blood is no longer delivered to the body’s tissues. The phenomenon is a macabre optical illusion, not a postmortem growth spurt.

Here’s a refreshing one, literally. Many people think that drinking a beverage like coffee or an alcoholic beer will effectively combat dehydration on a hot day or after a workout. This common belief is dangerously false. Both alcohol and caffeine are diuretics, meaning they prompt your body to increase the production of urine, leading to a net loss of fluids. While you are consuming liquid, you are also signaling your kidneys to flush out even more water and electrolytes than you normally would. For proper rehydration, nothing beats pure water or an electrolyte-balanced sports drink if you’ve been sweating profusely. Relying on a diuretic when you are already dehydrated can actually worsen the condition, leaving you more fatigued and susceptible to heat-related illnesses. It’s a crucial piece of knowledge for anyone who enjoys an active lifestyle.

Let’s talk about a famous inventor. The story goes that Thomas Edison invented the light bulb in a singular moment of genius. While Edison played a monumental role in making electric lighting practical and commercially viable, the statement that he invented it from scratch is false. The concept of incandescent light—heating a filament until it glows—had been around for decades before Edison’s famous Menlo Park laboratory went to work. Numerous other inventors had created prototype light bulbs, but they were plagued by problems like short lifespans, high cost, and inefficient energy use. Edison’s true, and arguably more impressive, genius was in developing a long-lasting carbon filament, creating a superior vacuum inside the bulb, and designing an entire electrical generation and distribution system to make the light bulb useful for the average person. His work was one of brilliant refinement and system-building, not a solitary act of creation from nothing.

This next one is a classic of playground logic and cartoon physics. The belief that a penny dropped from the top of a very tall building, like the Empire State Building, could kill a person on the sidewalk below is a dramatic exaggeration that is essentially false. A penny is aerodynamically poor; it’s small, light, and flat, causing it to flutter and tumble as it falls. This tumbling creates a tremendous amount of air resistance, which prevents the coin from ever reaching a truly lethal velocity. In fact, by the time it reached the ground, it would be traveling at a speed that would sting, certainly, but not even break the skin. The terminal velocity of a falling penny is simply not enough to turn it into a deadly projectile, despite how frightening the idea might seem when you’re looking down from a great height.

Let’s venture into the realm of astronomy. The proposition that the Earth is the closest planet to the sun is a straightforward false statement. Mercury holds that distinction, and it’s not even a close contest in our solar system lineup. However, this leads to a more interesting and counterintuitive fact: on average, Mercury is the closest planet to every other planet in the solar system. Because of its small orbit so close to the sun, it never strays too far from our star, and its average distance to any given outer planet ends up being less than the average distance between that outer planet and any of its other neighbors. It’s a fascinating statistical quirk of orbital mechanics that upends our linear thinking about the solar system.

Here’s a biological head-scratcher. The claim that humans have five senses is one we learn as children and rarely question, but from a scientific standpoint, it is a gross oversimplification that is functionally false. Beyond the classic sight, smell, taste, touch, and hearing, neurologists recognize many more. These include proprioception (your sense of where your body parts are in space), thermoception (the sense of temperature), nociception (the sense of pain), equilibrioception (the sense of balance), and chronoception (the sense of time passing). Some researchers list up to twenty or more distinct senses. The classic five are a framework inherited from the ancient Greek philosopher Aristotle, and while it’s a convenient model, it doesn’t come close to capturing the rich, complex symphony of sensory information our brains are constantly processing.

Let’s consider another piece of historical “common sense.” The idea that Vikings wore horned helmets into battle is an iconic image, but it is completely and utterly false. There is no archaeological evidence from any Viking burial site to support this. The practical Vikings would have found such headgear a ridiculous hindrance in close combat, as the horns could easily be grabbed by an opponent or could snag on shields and weapons. The myth was largely popularized in the 19th century, particularly by costume designers for Richard Wagner’s opera cycle Der Ring des Nibelungen, who added the horns for a more dramatic, barbaric look. The historical Viking warrior likely wore a simple, functional conical helmet made of iron or leather, or no helmet at all.

This next one is a matter of taste and science. The idea that there are distinct regions on your tongue dedicated exclusively to specific tastes—sweet on the tip, bitter at the back, etc.—is a persistent piece of misinformation that is false. This concept, known as the “tongue map,” originated from a misinterpretation of a 1901 German study. While it is true that some parts of the tongue may be slightly more sensitive to certain tastes, all regions of the tongue containing taste buds can detect the five basic tastes: sweet, sour, salty, bitter, and umami. The myth persists because it’s a simple, neat model that is easy to teach, but the reality of gustation is far more complex and integrated.

Let’s talk about a colossal creature from the past. The statement that the Tyrannosaurus rex could run at speeds comparable to a modern car, say 45 miles per hour, is a thrilling thought but one that biomechanical studies have shown to be almost certainly false. Paleontologists have built complex digital models of a T. rex skeleton and have studied the strength of its bones and the musculature required for such speed. The consensus now is that due to its immense size and weight, a T. rex running that fast would have experienced forces that would have shattered its leg bones. Estimates for its top speed are now much more modest, likely in the range of 12 to 15 miles per hour, which was still plenty fast enough to catch the slower-moving herbivores it probably preyed upon. It was more of a powerful, relentless walker than a sprinter.

Here’s a question of physics and perception. The proposition that a bolt of lightning never strikes the same place twice is a hopeful saying that is demonstrably false. In reality, lightning is strongly attracted to the tallest and most conductive objects in an area. The Empire State Building, for instance, is struck by lightning an average of about 25 times each year. A single thunderstorm can send multiple bolts into the same tree or radio tower. The path of ionized air created by the first strike can actually make it easier for a subsequent lightning bolt to follow the same path, making some locations perennial targets during an electrical storm.

Let’s delve into a culinary myth. Many home cooks believe that searing a steak “seals in the juices,” resulting in a more moist and tender final product. This is a classic kitchen wisdom that, when put to the scientific test, turns out to be false. Searing creates a wonderful, flavorful crust through the Maillard reaction, which is a fantastic reason to do it, but it does not create a waterproof barrier. In fact, well-done, seared meat can lose even more of its internal moisture than meat cooked gently without a sear. The key to a juicy steak is ultimately the final internal temperature and allowing it to rest after cooking, which lets the muscle fibers reabsorb some of the expelled juices. The sear is for flavor, not for locking in moisture.

This next one is a matter of simple physics. The claim that you can see the Great Wall of China from the moon is an even more extreme version of the space visibility myth and is, without a doubt, false. From the moon, which is nearly a thousand times farther away than a low Earth orbit, the Earth appears as a beautiful blue and white marble. No human-made structure, no matter how grand, is visible to the naked eye from that distance. It would be like trying to see a single human hair from several miles away. The grandeur of human achievement, while immense on our scale, is vanishingly small on the cosmic scale.

Let’s consider a piece of animal folklore. The belief that ostriches bury their heads in the sand when they are frightened is a pervasive image, but it is completely false. Ostriches do not engage in this behavior. The myth likely arose because from a distance, an ostrich feeding on the ground might appear to have its head buried, as it sometimes pecks at dirt or sand to ingest small stones and grit that aid its digestion. Furthermore, when an ostrich lies flat on the ground to camouflage itself from predators, its long neck and head, which are lightly colored, can blend in with the soil, creating an illusion from afar that its head is submerged. In reality, the ostrich’ main defense is its powerful legs, capable of delivering a kick that can kill a lion.

Here’s a question of human biology. The statement that we lose most of our body heat through our heads is a piece of advice often given to encourage wearing a hat in cold weather, but it is misleading and mostly false. The amount of heat lost from any part of your body is primarily determined by how much skin is exposed. Your head represents about 7 to 10 percent of your body’s surface area, and in a thermally neutral situation, it will lose a proportional amount of heat. The reason this myth took hold is that when people are outside in the cold, they often are fully bundled up with a coat, gloves, and pants, but leave their heads uncovered. In that scenario, the head does become a significant source of heat loss, but only because it’s the only part that’s exposed, not because it’s a special thermal vent.

Let’s talk about a fundamental force. The proposition that water flowing down a drain in the Northern Hemisphere always spins counter-clockwise due to the Coriolis effect is a classic piece of scientific trivia that is false when applied to small scales like a sink or a toilet. The Coriolis effect is a real force caused by the Earth’s rotation that influences large, slow-moving systems like hurricanes and ocean currents. However, for the small amount of water in a draining basin, the force of the Coriolis effect is minuscule compared to the other forces at play, such as the shape of the basin, any residual motion in the water from when it was filled, and the angle of the drain. The direction of your sink’s whirlpool is determined by these local factors, not by your hemisphere.

This next one is a matter of historical record. The idea that Napoleon Bonaparte was exceptionally short is a stereotype that has followed him for centuries, but it is historically false. At the time of his death, Napoleon was measured as being 5 feet 2 inches in French units. However, the French inch of the early 19th century was longer than the British inch. When converted, his height was a perfectly average 5 feet 6 inches or 7 inches for a Frenchman of his time. The myth of his short stature was largely British propaganda, which often referred to him as “the little corporal” to diminish his formidable reputation. The confusion over measurement systems cemented an image of a small, angry man that persists to this day.

Let’s consider a zoological fact. The statement that a dog’s mouth is cleaner than a human’s mouth is a comforting thought for those who receive slobbery kisses, but from a microbiological perspective, it is false. Both mouths are full of bacteria, but they are full of different kinds of bacteria, each specialized for their respective host. A dog’s mouth contains bacteria that help it process raw meat and clean its own fur, some of which can be harmful to humans if introduced into a wound. While a dog’s saliva does have some antibacterial properties that aid in healing their own wounds, the overall bacterial load is not inherently “cleaner.” It’s just different, and not necessarily something you’d want to swap with.

Here’s a question of sensory biology. The belief that bulls are enraged by the color red is a central image in the culture of bullfighting, but it is a complete falsehood. Bulls, like most other cattle, are dichromats, meaning they are essentially red-green colorblind. The color of the cape, or muleta, is irrelevant. What actually provokes the bull is the threatening, erratic movement of the cape itself. The reason matadors traditionally use a red cape is largely symbolic and theatrical; the color red is dramatic for the audience and helps to mask the stains of the bull’s blood, making the spectacle less gruesome for spectators. The bull is charging the motion, not the hue.

Let’s look at a piece of space science. The proposition that the dark side of the moon is perpetually dark is a misunderstanding of astronomical terms that is false. The moon is tidally locked with the Earth, meaning it takes the same amount of time to rotate on its axis as it does to orbit the Earth, so we only ever see one side from our planet. However, as the moon orbits the Earth, the side that we don’t see—often incorrectly called the “dark side”—goes through a full cycle of sunlight and darkness, just like the side we see. When we see a new moon, the “far side” is fully illuminated, and when we see a full moon, the far side is in total darkness. It’s more accurately called the “far side,” not the dark side.

This next one is a matter of botanical life. The idea that the venus flytrap must be fed meat to survive like an animal is a common misconception that is false. While the venus flytrap is a carnivorous plant that can digest insects, it does so to supplement nutrients that are scarce in its native, nitrogen-poor soil environments, not for energy. Like all other plants, it generates its primary energy through photosynthesis. It can survive perfectly well without ever catching a single insect, but it will likely grow more slowly and be less robust. The trapping mechanism is a brilliant adaptation for nutrient acquisition, not a replacement for its fundamental role as a sunlight-powered organism.

Let’s talk about a psychological effect. The belief that you should never wake a sleepwalker is a long-standing piece of folk advice that, while well-intentioned, is mostly false. The real danger is not in waking them, but in the potential for them to be startled and confused, which could lead to them lashing out or injuring themselves in a panic. However, leaving a sleepwalker to wander unsupervised is far more dangerous, as they can walk into traffic, fall down stairs, or otherwise harm themselves. The recommended course of action is to gently and calmly guide them back to their bed without making a loud, sudden effort to jolt them awake. Their safety is the paramount concern.

Here’s a final historical puzzle. The claim that the Liberty Bell cracked dramatically upon its first ringing in 1776 is a wonderful patriotic story, but it is historically false. The bell was cast in 1751 in London and cracked upon its very first test ring in Philadelphia in 1752, long before the American Revolution. It was recast twice by local artisans, John Pass and John Stow, whose names are inscribed on it. The bell was used for decades to call lawmakers to sessions and to summon citizens for announcements. The familiar, large crack that we see today developed slowly over time, and the final, rendering crack that silenced it occurred in the 1840s while it was being tolled for George Washington’s birthday. Its association with liberty and independence came later, through the efforts of 19th-century abolitionists who adopted it as a symbol.

So, how did you fare with these thirty true or false questions? The real value of this exercise, I find, isn’t just in a final score, but in the fascinating detours our minds take when confronted with the gap between common belief and verifiable reality. Each of these little puzzles serves as a reminder that the world is often more nuanced and surprising than our assumptions would have us believe. It encourages a healthy skepticism and a curious mind, prompting us to ask “is that really true?” more often. I hope this journey through myths, misconceptions, and marvelous facts has been as entertaining for you as it was for me to put together, and that it leaves you looking at the world with a slightly more inquisitive and discerning eye, ready to challenge the next piece of “common knowledge” that comes your way.