Seventeenth-century Danish geologist Nicolas Steno earned his chops at a young age, studying cadavers and drawing anatomic connections between species. Steno made outsized contributions to the field of geology, influencing Charles Lyell, James Hutton and Charles Darwin. Addison Anderson recounts Steno's little-known legacy and lauds his insisten...

A 2006 study took a class of surgical residents and split them into two groups. Each received the same study materials, but one group was told to use specific study methods. When tested a month later, this group performed significantly better than the other residents. So, what were these methods? Explore how the brain learns and stores informati...

Some people love the feeling of cracking their knuckles, while others cringe at the sound. But what causes that trademark pop? And is it dangerous? Eleanor Nelsen gives the facts behind joint popping. [Directed by Steve Belfer Creative, narrated by Addison Anderson].

It's so obvious that it's practically proverbial: you can't unboil an egg. But actually, it turns out that you can -- sort of. Eleanor Nelsen explains the process by which mechanical energy can undo what thermal energy has done. [Directed by Província Studio, narrated by Addison Anderson].

Halitosis is a curse that has plagued humanity since ancient times. But what causes it, and why is it so universally terrifying? Mel Rosenberg outlines the basics of bad breath — and what you can do when it strikes you. [Directed by Andrew Foerster, narrated by Addison Anderson, music by Devin Polaski].

One hundred green-eyed logicians have been imprisoned on an island by a mad dictator. Their only hope for freedom lies in the answer to one famously difficult logic puzzle. Can you solve it? Alex Gendler walks us through this green-eyed riddle. [Directed by Artrake Studio, narrated by Addison Anderson].

When under anesthesia, you can't move, form memories, or — hopefully — feel pain. And while it might just seem like you are asleep for that time, you actually aren't. What's going on? Steven Zheng explains what we know about the science behind anesthesia. [Directed by Zedem Media, narrated by Addison Anderson].

You've probably heard that carbon dioxide is warming the Earth. But how exactly is it doing it? Lieven Scheire uses a rainbow, a light bulb and a bit of quantum physics to describe the science behind global warming. [Directed by STK Films, narrated Addison Anderson, music by Michael Dow].

Perpetual motion machines — devices that can do work indefinitely without any external energy source — have captured many inventors' imaginations because they could totally transform our relationship with energy. There's just one problem: they don't work. Why not? Netta Schramm describes the pitfalls of perpetual motion machines. [Directed by TE...

In standard notation, rhythm is indicated on a musical bar line. But there are other ways to visualize rhythm that can be more intuitive. John Varney describes the 'wheel method' of tracing rhythm and uses it to take us on a musical journey around the world. [Directed by TED-Ed, narrated by Addison Anderson].

Ah, spring. Grass growing, flowers blooming, trees budding. For those with allergies, though, this explosion of new life probably inspires more dread than joy. So what's behind this annual onslaught of mucus? Eleanor Nelsen explains what happens when your immune system goes rogue. [Directed by Lisa LaBracio, narrated by Addison Anderson, music b...

Would mathematics exist if people didn't? Did we create mathematical concepts to help us understand the world around us, or is math the native language of the universe itself? Jeff Dekofsky traces some famous arguments in this ancient and hotly debated question. [Directed by The Tremendousness Collective, narrated by Addison Anderson].

About 66 million years ago, a terrible extinction event wiped out the dinosaurs. But it wasn’t the only event of this kind -- extinctions of various severity have occurred throughout the Earth’s history — and are still happening all around us today. Borths, D'Emic, and Pritchard give a quick history of mass extinctions. [Directed by Juliette Mar...

In the United States today, if you are over eighteen, a citizen, and the resident of a state, you can vote (with some exceptions). So, how have voting rights changed since the first election in 1789? Nicki Beaman Griffin outlines the history of the long fight for a more inclusive electorate. [Directed by Darcy Vorhees, narrated by Addison Anders...

When you think of Archimedes' Eureka moment, you probably imagine a man in a bathtub, right? As it turns out, there's much more to the story. Armand D'Angour tells the story of Archimedes' biggest assignment -- an enormous floating palace commissioned by a king -- that helped him find Eureka. [Directed by Zedem Media, narrated by Addison Anderso...

Narcissism isn't just a personality type that shows up in advice columns; it's actually a set of traits classified and studied by psychologists. But what causes it? And can narcissists improve on their negative traits? W. Keith Campbell describes the psychology behind the elevated and sometimes detrimental self-involvement of narcissists. [Direc...

As simple as it seems, it's often impossible to accurately translate the word "you" without knowing a lot more about the situation where it's being said. Krystian Aparta describes the specific reasons why it can be difficult, citing examples from many different languages. [Directed by Avi Ofer, narrated by Addison Anderson, music by Wonder Boy A...

In the United States, it's estimated that 30 percent of adults and 66 percent of adolescents are regularly sleep-deprived. This isn't just a minor inconvenience: staying awake can cause serious bodily harm. Claudia Aguirre shows what happens to your body and brain when you skip sleep. [Directed by TED-Ed, narrated by Addison Anderson, music by C...

We've all been told that we should recycle plastic bottles and containers. But what actually happens to the plastic if we just throw it away? Emma Bryce traces the life cycles of three different plastic bottles, shedding light on the dangers these disposables present to our world. [Directed by Sharon Colman, narrated by Addison Anderson, music b...

Pascal's triangle, which at first may just look like a neatly arranged stack of numbers, is actually a mathematical treasure trove. But what about it has so intrigued mathematicians the world over? Wajdi Mohamed Ratemi shows how Pascal's triangle is full of patterns and secrets. [Directed by Henrik Malmgren, narrated by Addison Anderson, music b...

Hatshepsut was a female pharaoh during the New Kingdom in Egypt. Twenty years after her death, somebody smashed her statues, took a chisel and attempted to erase the pharaoh’s name and image from history. But who did it? And why? Kate Green investigates Hatshepsut's history for clues to this ancient puzzle. [Directed by Steff Lee, narrated by Ad...

Everyone experiences pain -- but why do some people react to the same painful stimulus in different ways? And what exactly is pain, anyway? Karen D. Davis walks you through your brain on pain, illuminating why the "pain experience" differs from person to person. [Directed by Brett Underhill, narrated by Addison Anderson].

The milk industry produces in excess of 840 million tons of products each year. Why do humans drink so much milk? And given that all mammals lactate, why do we favor certain types of milk over others? Jonathan J. O’Sullivan describes how milk is made. [Directed by Biljana Labović, narrated by Addison Anderson].

Lake Maracaibo is the stormiest place on the planet. Thunderstorms rage above this massive body of water for up to 200 days of the year, with each ear-splitting event lasting for several hours. But why? Graeme Anderson lists the factors that create Lake Maracaibo's seemingly ever-lasting storms. [Directed by D. Lee Peffer II, narrated by Addison...

Octopuses have the ability to solve puzzles, learn through observation, and even use tools – just like humans. But what makes octopus intelligence so amazing is that it comes from a biological structure completely different from ours. Cláudio L. Guerra takes a look inside the amazing octopus brain. [Directed by Cinematic, narrated by Addison And...

How do you know you're real? Is existence all just a big dream? Has some mad scientist duped us into simply believing that we exist? James Zucker investigates all of these questions (and more) in this mind-boggling tribute to René Descartes's "Meditations on First Philosophy." [Directed by Stretch Films, Inc., narrated by Addison Anderson].

Mathematics explains the workings of the universe, from particle physics to engineering and economics. Math is even closely related to music, and their common ground has something to do with a Rubik's Cube puzzle. Michael Staff explains how group theory can teach us to play a Rubik’s Cube like a piano. [Directed by Shixie, narrated by Addison An...

This is episode 10 of our animated series "Think Like A Coder." This 10-episode narrative follows a girl, Ethic, and her robot companion, Hedge, as they attempt to save the world. The two embark on a quest to collect three artifacts and must solve their way through a series of programming puzzles. [Directed by Kozmonot Animation Studio, narrated...

This is episode 9 of our animated series "Think Like A Coder." This 10-episode narrative follows a girl, Ethic, and her robot companion, Hedge, as they attempt to save the world. The two embark on a quest to collect three artifacts and must solve their way through a series of programming puzzles. [Directed by Kozmonot Animation Studio, narrated ...

The classical physics that we encounter in our everyday, macroscopic world is very different from the quantum physics that governs systems on a much smaller scale (like atoms). One great example of quantum physics' weirdness can be shown in the Schrödinger's cat thought experiment. Josh Samani walks us through this experiment in quantum entangle...