High school curricula have a difficult task—to give students a fundamental understanding of a range of subjects with a limited time and budget. Understandably, they frequently make mistakes, over-simplify complex processes, and quickly become outdated. Here are 20 “facts” you may have learned in high school that require a closer look.
All Mammals Give Birth to Live Young
All mammals are warm-blooded animals with hair or fur that nurse their young with milk from mammary glands. However, according to the UCMP, one group (called the monotremes) lays soft, leathery eggs—four species of echidna and the duck-billed platypus. They are all survivors of ancient mammal species that evolved in and around Australia.
Atoms Are Compact
An atom consists of a tiny, dense nucleus at its center, containing protons and neutrons, but the rest of an atom is mostly space. Circling the nucleus at a much larger distance are electrons, and this space is much larger than the nucleus itself. If we removed all the empty space from our solar system, the planets would be the size of marbles, and the sun would be a grapefruit!
The Amazon Produces Most of the World’s Oxygen
This is a common misconception based on the fact that the Amazon Rainforest is a huge and productive ecosystem that does indeed produce oxygen thanks to an abundance of terrestrial green plants. Yet it cannot compare with the sheer biomass of phytoplankton, microscopic marine algae responsible for producing an estimated 50–80% of the world’s oxygen.
The Great Wall of China Is Visible from Space
Typically, the Great Wall is not discernible from orbit, although a very experienced astronaut may be able to make it out under ideal atmospheric conditions, provided they are also in low orbit and the perfect location. It is possible to see very large human structures, such as major highways, dams, and the urban sprawl of major cities like London, Paris, and Tokyo.
We Only Use 10% of Our Brains
This pervasive myth has been around for over a century and originates from the fact that we never use 100% of our brains at once—that would be cognitive and electrical overload, akin to having a major seizure. Brain imaging studies have shown that different parts of the brain are constantly active, even during sleep, but most parts only ‘turn on’ when needed.
The Wright Brothers Invented the First Airplane
Air and Space asserts that the Wright Brothers were pioneers in aviation and completed the first sustained flight by a heavier-than-air flying machine powered and controlled by a man in December 1903. But they weren’t the first to conceive or build a flying machine, with many less successful inventors having already produced several gliders and airplanes.
Sugar Always Turns into Fat
Sugar itself isn’t inherently bad, but consuming excessive amounts can negatively affect your teeth and blood sugar levels and can also contribute to weight gain. The human body can (and does) convert excess sugar into fat for storage, but it’s not a simple or immediate process. Overall calorie intake, exercise, and metabolism all play an important role.
Benjamin Franklin Discovered Electricity
The ancient Greeks observed static electricity as early as 600 BC, over 2000 years before Benjamin Franklin was even born! Although Franklin’s contributions to electrical science were groundbreaking, he didn’t ‘discover’ it. His famous kite experiment in 1752 wasn’t actually about proving electricity existed but about showing that lightning was a form of electrical energy.
Cracking Your Knuckles Causes Arthritis
Cracking your knuckles can be annoying, but it won’t destroy the cartilage in your finger joints or damage your bones. Scientific studies have shown that the popping sound is caused by gas bubbles bursting in the synovial fluid within your knuckles. This is harmless, although excessive knuckle cracking might irritate the ligaments and tendons, causing temporary aches.
Humans Evolved from Chimpanzees
This oversimplification of the primate family tree fails to understand how evolution works. The Smithsonian writes, “We do share a common ape ancestor with chimpanzees. It lived between 8 and 6 million years ago. But humans and chimpanzees evolved differently from that same ancestor.” We were the same species at one point, but populations split off and evolved—one did not become the other.
Reading in Dim Light Damages Your Eyes
Reading in very low light can cause temporary eye strain, but it won’t permanently damage your vision. If you are reading in poor light and experience headaches, blurry vision, and fatigue, these symptoms can indicate eye strain. You just need to rest your eyes by sleeping or keeping them closed for an extended period, but you will not suffer any permanent ocular damage.
Baldness Comes from the Maternal Side
While genetics do play a role in hair loss, the inheritance pattern for baldness is much more complicated than simply looking at your maternal grandfather’s head! As with every inherited trait, genes from both parents contribute to male and female pattern baldness. The expression of these genes can also vary depending on hormones and lifestyle factors, such as stress.
Opossums Can Choose to Play Dead for Hours
This is another myth based on truth that requires clarification. When threatened, opossums enter a state of unconsciousness as a defense mechanism, making them appear lifeless to predators. This can last for up to an hour, but it’s not a conscious act. The opossum itself can’t control it. Their body temperature involuntarily drops, their heart rate slows, and their muscles become limp.
We Taste Only with Our Tongues
Taste buds located on the tongue play a vital role in taste perception, but anyone who’s ever had a head cold will wonder why they can’t taste food with a blocked nose. This is because our sense of taste is a combination of taste buds and olfactory receptors in the nasal cavity. The smell is crucial in flavor perception, and holding your nose will mute even powerful tastes.
Bulls Are Angered by the Color Red
Bulls are almost entirely colorblind and are primarily sensitive to shades of blue and yellow, not red. The red cape used in bullfighting triggers the bull because of its movement and erratic waving. The bull is bred to be aggressive and reactive and is typically already stressed and/or wounded. The color of the cape is traditional but unimportant to the bull.
Sugar Causes Cavities
Sugar itself doesn’t cause cavities. If your mouth were sterile, sugar would have no impact on your teeth whatsoever! Prescott Dentistry reports that sugar is a food source for oral bacteria that produce acid as a by-product of feeding, and it’s this acid that erodes your enamel and causes cavities. Both refined sugars and carbohydrates inadvertently increase acid production.
Gold Is the Most Valuable Metal
When we think of precious metals, gold is often the first one that comes to mind. Although it’s a relatively rare and high-value metal, it’s not the most expensive. Rarer metals with even higher price tags are used for scientific and technical purposes rather than jewelry. An example is rhodium, a platinum group metal used in catalytic converters.
Celery Burns More Calories Than It Contains
This is a misconception about the thermic effect of food (TEF), which is the energy your body expends to digest and absorb food. Yes, celery is tough to break down and has a low calorific value, but the ‘indigestible’ parts pass through your body—your digestive system doesn’t waste lots of valuable energy on extracting what little calories there are in the woody parts.
Electricity Travels at the Speed of Light
Electricity travels incredibly fast, but not quite at the speed of light. It can typically travel at up to 90% light speed, which is approximately 270,000 km/s! The speed of electricity also depends on other factors, like the conductor it’s traveling through. In a typical wire, electricity travels at around one-third to two-thirds the speed of light due to electrical resistance.
The Population of the Earth Is Exploding
The global population has been growing since the Industrial Revolution. Improved living conditions, medicine, nutrition, and technological advancements have improved human survival rates, boosted fertility, and extended our lifespans. However, the growth rate has been slowing down in recent decades, and The United Nations estimates that the world population will begin to decline by 2100.
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