The microraptor was a four-winged carnivorous dinosaur with iridescent black feathers. But if our information about this dinosaur comes from fossils, how can we be certain about its color? Len Bloch shows how making sense of the evidence requires careful examination of the fossil and a good understanding of the physics of light and color. Lesson by Len Bloch, animation by Paul Newell.

The things we eat and drink on a daily basis can impact our health in big ways. Too many carbohydrates, for instance, can lead to insulin resistance, which is a major contributor to cardiovascular disease and Type 2 Diabetes. But what are carbs, exactly? And what do they do to our bodies? Richard J. Wood explains. [Directed by Qa'ed Mai, narrated by Addison Anderson].

Symmetry is everywhere in nature. And we usually associate it with beauty: a perfectly shaped leaf or a butterfly with intricate patterns mirrored on each wing. But it turns out that asymmetry is pretty important, too — and more common than you might think. Leo Q. Wan takes us into the human body to show how biological asymmetry can be quite beautiful. [Directed by Echo Bridge Pictures, narrated by Addison Anderson].

Your expedition finally stands at the heart of the ancient temple. But as you study the inscriptions in the darkness, two wisps of green smoke burst forth. The walls begin to shake. The giant sandglass begins flowing with less than an hour before it empties, and a rumbling tells you that you don't want to be around when that happens. Can you use math to escape the temple? Dennis E. Shasha shows how. [Directed by Artrake Studio, narrated by Addison Anderson].

Our early ancestors relied on lightning to cause forest fires, from which they could collect coals and burning sticks to help them cook food and clear land. Yet, it wasn’t just humans who benefited from these natural phenomena. Even as they destroyed trees, fires also helped the forests themselves. Jim Schulz outlines the benefits of wildfire. Lesson by Jim Schulz, animation by Provincia Studio.

After the French Revolution erupted in 1789, Europe was thrown into chaos. Neighboring countries' monarchs feared they would share the fate of Louis XVI and attacked the new Republic, while at home, extremism and mistrust between factions led to bloodshed. In the midst of all this conflict, Napoleon emerged. But did he save the revolution, or destroy it? Alex Gendler puts Napoleon on trial. [Directed by Brett Underhill, narrated by Addison Anderson].

Ah, romantic love; beautiful and intoxicating, heart-breaking and soul-crushing... often all at the same time! If romantic love has a purpose, neither science nor psychology has discovered it yet – but over the course of history, some of our most respected philosophers have put forward some intriguing theories. Skye C. Cleary outlines five of these philosophical perspectives on why we love. [Directed by Avi Ofer, narrated by Addison Anderson, music by Brooks Ball and Cem Misirlioglu].

Have you ever talked with a friend about a problem, only to realize that he just doesn't seem to grasp why the issue is so important to you? Have you ever presented an idea to a group, and it's met with utter confusion? What's going on here? Katherine Hampsten describes why miscommunication occurs so frequently, and how we can minimize frustration while expressing ourselves better. [Directed by Andrew Foerster, narrated by Addison Anderson].

When we hear the word radiation, it's tempting to picture huge explosions and frightening mutations. But that's not the full story — radiation also applies to rainbows and a doctor examining an X-ray. So what is it, really, and how much should we worry about its effects? Matt Anticole describes the different types of radiation. [Directed by Tinmouse Animation Studio, narrated by Addison Anderson].

Every day, a sea of decisions stretches before us, and it's impossible to make a perfect choice every time. But there are many ways to improve our chances — and one particularly effective technique is critical thinking. Samantha Agoos describes a 5-step process that may help you with any number of problems. [Directed by Nick Hilditch, narrated by Addison Anderson].

Steel and plastic are essential to much of our infrastructure and technology. Steel is strong and hard, but difficult to shape intricately. Plastic can take on just about any form, but it’s weak and soft. Wouldn’t it be nice if there were one material as strong as the strongest steel and as shapeable as plastic? Ashwini Bharathula discusses the future of metallic glass. Lesson by Ashwini Bharathula, animation by Tinmouse Animation Studio.

Your rich, eccentric uncle just passed away, and you and your 99 nasty relatives have been invited to the reading of his will. He wanted to leave all of his money to you, but he knew that if he did, your relatives would pester you forever. Can you solve the riddle he left for you and get the inheritance? Lisa Winer shows how. [Directed by Artrake Studio, narrated by Addison Anderson].

Water is essentially everywhere in our world, and the average human is composed of between 55 and 60% water. So what role does water play in our bodies, and how much do we actually need to drink to stay healthy? Mia Nacamulli details the health benefits of hydration. [Directed by Chris Bishop, narrated by Addison Anderson].

How do schools of fish swim in harmony? How do the tiny cells in your brain give rise to the complex thoughts, memories, and consciousness that are you? Oddly enough, those questions have the same general answer. Nathan S. Jacobs explains the concept of emergence, the spontaneous creation of sophisticated behaviors and functions from large groups of simple elements. [Directed by Lisa LaBracio, narrated by Addison Anderson, music by Wonder Boy Audio].

The placebo effect is an unexplained phenomenon wherein drugs, treatments, and therapies that aren't supposed to have an effect — and are often fake — miraculously make people feel better. What's going on? Emma Bryce dives into the mystery of placebos' bizarre benefits. [Directed by Hernando Bahamon, narrated by Addison Anderson].

It starts with a tickle in your throat that becomes a cough. Your muscles begin to ache, you grow irritable, and you lose your appetite. It's official: you've got the flu. It's logical to assume that this miserable medley of symptoms is the result of the infection coursing through your body — but is that really the case? Marco A. Sotomayor explains what's actually making you feel sick. [Directed by Henrik Malmgren, narrated by Addison Anderson, music by GoodJobStudios].

It can be hard sometimes, when speaking, to remember all of the grammatical rules that guide us when we're writing. When is it right to say "the dog and me" and when should it be "the dog and I"? Does it even matter? Andreea S. Calude dives into the age-old argument between linguistic prescriptivists and descriptivists — who have two very different opinions on the matter. [Directed by Mike Schell, narrated by Addison Anderson].

Imagine a police lineup where ten witnesses are asked to identify a bank robber they glimpsed fleeing the scene. If six of them pick the same person, there's a good chance that's the culprit. And if all ten do, you might think the case is rock solid. But sometimes, the closer you start to get to total agreement, the less reliable the result becomes. Derek Abbott explains the paradox of unanimity. [Directed by Brett Underhill, narrated by Addison Anderson].

It starts with a tickle in your throat that becomes a cough. Your muscles begin to ache, you grow irritable, and you lose your appetite. It’s official: you’ve got the flu. It’s logical to assume that this miserable medley of symptoms is the result of the infection coursing through your body — but is that really the case? Marco A. Sotomayor explains what’s actually making you feel sick. Lesson by Marco A. Sotomayor, animation by Henrik Malmgren.

What is consciousness? Can an artificial machine really think? For many, these have been vital considerations for the future of artificial intelligence. But British computer scientist Alan Turing decided to disregard all these questions in favor of a much simpler one: Can a computer talk like a human? Alex Gendler describes the Turing test and details some of its surprising results. Lesson by Alex Gendler, animation by Patrick Smith.

In many ways, our memories make us who we are, helping us remember our past, learn and retain skills, and plan for the future. And for the computers that often act as extensions of ourselves, memory plays much the same role. Kanawat Senanan explains how computer memory works. [Directed by TED-Ed, narrated by Addison Anderson, music by Carlos Palomares].

Often people make decisions that are not "rational" from a purely economical point of view — meaning that they don't necessarily lead to the best result. Why is that? Are we just bad at dealing with numbers and odds? Or is there a psychological mechanism behind it? Sara Garofalo explains heuristics, problem-solving approaches based on previous experience and intuition rather than analysis. [Directed by TOGETHER, narrated by Pen-Pen Chen].

Why can we find geometric shapes in the night sky? How can we know that at least two people in London have exactly the same number of hairs on their head? And why can patterns be found in just about any text — even Vanilla Ice lyrics? PatrickJMT describes the Ramsey theory, which states that given enough elements in a set or structure, some interesting pattern among them is guaranteed to emerge. [Directed by Aaron, Sean & Mathias Studios, narrated by Addison Anderson, music by Manuel Borda].

As your country's top spy, you must infiltrate the headquarters of the evil syndicate, find the secret control panel, and deactivate their death ray. But your reconnaissance team is spotty, and you have only limited information about the control panel's whereabouts. Can you solve the control room riddle and deactivate their weapon in time? Dennis Shasha shows you how. [Directed by Zedem Media, narrated by Addison Anderson].

Language is complex, and when abstract or nuanced concepts get lost in translation, the consequences may be catastrophic. Given the complexities of language and cultural exchange, how do these epic miscommunications not happen all the time? Ewandro Magalhaes explains how much of the answer lies with the skill and training of interpreters to overcome language barriers. [Directed by Andrew Foerster, narrated by Addison Anderson].

Human bodies aren't built for extreme aging: our capacity is set at about 90 years. But what does aging really mean, and how does it counteract the body's efforts to stay alive? Monica Menesini details the nine physiological traits that play a central role in aging. [Directed by Cinematic, narrated by Pen-Pen Chen].

About 60 million people around the globe have been forced to leave their homes to escape war, violence and persecution. The majority have become Internally Displaced Persons, meaning they fled their homes but are still in their own countries. Others, referred to as refugees, sought shelter outside their own country. But what does that term really mean? Benedetta Berti and Evelien Borgman explain. [Directed by Biljana Labovic, narrated by Susan Zimmerman, music by David Obuchowski and Peter Linder].

When it comes to what you bite, chew and swallow, your choices have a direct and long-lasting effect on the most powerful organ in your body: your brain. So which foods cause you to feel so tired after lunch? Or so restless at night? Mia Nacamulli takes you into the brain to find out. [Directed by Private Island, narrated by Addison Anderson].

Obesity is an escalating global epidemic. It substantially raises the probability of diseases like diabetes, heart disease, stroke, high blood pressure, and cancer. But what is the distinction between being overweight and being obese? And how does a person become obese? Mia Nacamulli explores obesity. [Directed by Kozmonot Animation Studio, narrated by Pen-Pen Chen, music by WORKPLAYWORK and Cem Misirlioglu].

In a dystopian world, your resistance group is humanity's last hope. Unfortunately, you've all been captured by the tyrannical rulers and brought to the ancient coliseum for their deadly entertainment. Will you be able to solve the passcode riddle and get everyone out safely? Ganesh Pai shows how. [Directed by Jun Zee Myers, narrated by Addison Anderson].

For the majority of recorded human history, units like the weight of a grain or the length of a hand weren't exact and varied from place to place. Now, consistent measurements are such an integral part of our daily lives that it's hard to appreciate what a major accomplishment for humanity they've been. Matt Anticole traces the wild history of the metric system. [Directed by Globizco, narrated by Addison Anderson, music by Manuel Borda].

The longest recorded case of hiccups lasted for 68 years ... and was caused by a falling hog. While that level of severity is extremely uncommon, most of us are no stranger to an occasional case of the hiccups. But what causes these 'hics' in the first place? John Cameron takes us into the diaphragm to find out. [Directed by Black Powder Design, narrated by Addison Anderson].

There’s an organism that changed the world. It caused the first mass extinction in Earth’s history … and also paved the way for complex life. How? Anusuya Willis explains how cyanobacteria, simple organisms that don’t even have nuclei or any other organelles, wrote a pivotal chapter in the story of life on Earth. Lesson by Anusuya Willis, animation by Augenblick Studios.

Imagine you're on a game show and you can choose between two prizes: a diamond ... or a bottle of water. It's an easy choice – the diamonds are more valuable. But if given the same choice when you were dehydrated in the desert, after wandering for days, would you choose differently? Why? Aren't diamonds still more valuable? Akshita Agarwal explains the paradox of value. [Directed by Qa'ed Mai, narrated by Julianna Zarzycki].

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 Audio].

Contraceptives are designed to prevent pregnancy in three basic ways: they either block sperm, disable sperm before they reach the uterus, or suppress ovulation. But is one strategy better than the other? And how does each one work? NWHunter describes the mechanics behind different kinds of contraceptives. [Directed by Draško Ivezić, narrated by Julianna Zarzycki].

Could human civilization eventually spread across the whole Milky Way galaxy? Could we move beyond our small, blue planet to establish colonies in the multitude of star systems out there? These questions are pretty daunting, but their (theoretical) answers were actually put forth decades ago. Roey Tzezana describes the conceptual von Neumann machine. [Directed by Eoin Duffy, narrated by Addison Anderson, music by Wesley Slover].

Your favorite band is great at playing music...but not so great at being organized. They keep misplacing their instruments on tour, and it's driving their manager mad. Can you solve the brain-numbing riddle their manager assigns them and make sure the band stays on their label? Yossi Elran shows how. [Directed by Artrake Studio, narrated by Addison Anderson].

Humans should urinate at least four to six times a day, but occasionally, the pressures of modern life force us to clench and hold it in. How bad is this habit, and how long can our bodies withstand it? Heba Shaheed takes us inside the bladder to find out. [Directed by Artrake Studio, narrated by Julianna Zarzycki].

When a team of archeologists recently came across some 15,000-year-old human remains, they made an interesting discovery: the teeth of those ancient humans were riddled with holes. So what causes cavities, and how can we avoid them? Mel Rosenberg takes us inside our teeth to find out. [Directed by Andrew Foerster, narrated by Addison Anderson, music by Devin Polaski].

Few individuals have influenced the world and many of today's thinkers like Plato. He created the first Western university and was teacher to Ancient Greece's greatest minds, including Aristotle. But even he wasn't perfect. Along with his great ideas, Plato had a few that haven't exactly stood the test of time. Wisecrack gives a brief rundown of a few of Plato's best and worst ideas. [Directed by Aaron, Tom and Mathias Studios, narrated by Addison Anderson].

As a wildfire rages through the grasslands, three lions and three wildebeest flee for their lives. To escape the inferno, they must cross over to the left bank of a crocodile-infested river. Can you help them figure out how to get across on the one raft available without losing any lives? Lisa Winer shows how. [Directed by Artrake Studio, narrated by Addison Anderson].

You work at the college library. You're in the middle of a quiet afternoon when suddenly, a shipment of 1,280 books arrives. The books are in a straight line, but they're all out of order, and the automatic sorting system is broken. How can you sort the books quickly? Chand John shows how, shedding light on how algorithms help librarians and search engines speedily sort information. [Directed by Anton Trofimov, narrated by Pen-Pen Chen].

Professor Fukanō, the famous scientist, has embarked on a new challenge – piloting around the world in a plane of his own design. There's just one problem: there's not enough fuel to complete the journey. Luckily, there are two other planes to help. Can you help the professor fly for the whole trip and achieve his dream, without anyone running out of fuel and crashing? Judd A. Schorr shows how. [Directed by Artrake Studio, narrated by Addison Anderson].

Teflon was in the spacesuits the Apollo crew wore for the moon landing, in pipes and valves used in the Manhattan project, and it may be in your kitchen, as the nonstick coating on frying pans and cookie sheets. So what is this slippery solid — and why doesn’t anything stick to it? Ashwini Bharathula describes the science behind Teflon. Lesson by Ashwini Bharathula, animation by Andrew Foerster.

Have you ever sat in a doctor's office for hours, despite having an appointment? Has a hotel turned down your reservation because it's full? Have you been bumped off a flight that you paid for? These are all symptoms of overbooking, a practice where businesses sell or book more than their capacity. So why do they do it? Nina Klietsch explains the math behind this frustrating practice. [Directed by Anton Trofimov, narrated by Addison Anderson].

After witnessing the “violent rage” shown by babies whenever deprived of an item they considered their own, Jean Piaget – a founding father of child psychology – observed something profound about human nature: Our sense of ownership emerges incredibly early. But why do we become so attached to things? Christian Jarrett details the psychology of ownership.

The stethoscope is the single most widely used medical instrument in the world. But where did the idea come from? In the seventh installment of our ‘Moments of Vision’ series, Jessica Oreck shares the modest origins of this incredibly useful item. Lesson and animation by Jessica Oreck.