TED-Ed

Until recently, many teachers only got one word of feedback a year: "satisfactory." And with no feedback, no coaching, there's just no way to improve. Bill Gates suggests that even great teachers can get better with smart feedback -- and lays out a program from his foundation to bring it to every classroom. Talk by Bill Gates. Learn more about your ad choices. Visit megaphone.fm/adchoices

Learn the techniques and tricks that pyramid schemes use to recruit new members and how to avoid being fooled yourself. --In 2004, a nutrition company offered a life-changing opportunity to earn a full-time income for part-time work. There were only two steps to get started: purchase a $500 kit and recruit two more members. By 2013, the company was making $200 million. There was just one problem -...

View full lesson: http://ed.ted.com/lessons/the-fundamentals-of-space-time-part-3-andrew-pontzen-and-tom-whyntieView part 1: http://ed.ted.com/lessons/the-fundamentals-of-space-time-part-1-andrew-pontzen-and-tom-whyntieView part 2: http://ed.ted.com/lessons/the-fundamentals-of-space-time-part-2-andrew-pontzen-and-tom-whyntieIn the first two lessons of this series on space-time, we've dealt with ob...

You don't need to plan an exotic trip to find creative inspiration. Just look up, says Gavin Pretor-Pinney, founder of the Cloud Appreciation Society. As he shares charming photos of nature's finest aerial architecture, Pretor-Pinney calls for us all to take a step off the digital treadmill, lie back and admire the beauty in the sky above. Talk by Gavin Pretor-Pinney. Learn more about your ad choi...

Dig into the false cause fallacy, which assumes that one event causes another, and learn how to distinguish between correlation and causation.--It’s 1843, and a debate is raging about one of the most common killers of women: childbed fever— no one knows what causes it. One physician has observed patients with inflammation go on to develop childbed fever, and therefore believes the inflammation cau...

Discover the quirky creature known as the parrotfish, and the key role it plays in keeping coral reefs healthy and thriving. --As the sun rises over a quiet coral reef, one animal breaks the morning silence. Named for its vibrant scales and beak-like teeth, the parrotfish devours a particularly crunchy breakfast: rocks. Why would any creature take bites out of the seafloor? Mike Gil explores how t...

View full lesson: http://ed.ted.com/lessons/the-strengths-and-weaknesses-of-acids-and-bases-george-zaidan-and-charles-mortonVinegar may have a powerful smell, but did you know it's actually a weak acid? In the chemical economy, acids actively give away their protons while bases actively collect them -- but some more aggressively than others. George Zaidan and Charles Morton use the currency of sub...

View full lesson: http://ed.ted.com/lessons/how-we-conquered-the-deadly-smallpox-virus-simona-zompiFor 10,000 years, humanity suffered from the scourge of smallpox. The virus killed almost a third of its victims within two weeks and left survivors horribly scarred. But Simona Zompi commends the brave souls -- a Buddhist nun, a boy, a cow, a dairymaid and physician Edward Jenner -- who first stoppe...

Explore the ancient methods of growing glaciers, the homemade bodies of ice used as water sources, and how they can be used to combat climate change. --In the 13th century, Genghis Khan embarked on a mission to take over Eurasia, swiftly conquering countries and drawing them into his empire. But, legend has it that there was one obstacle that even he couldn’t overcome: a towering wall of ice, grow...

Building a skyscraper? Forget about steel and concrete, says architect Michael Green, and build it out of ... wood. As he details in this intriguing talk, it's not only possible to build safe wooden structures up to 30 stories tall (and, he hopes, higher), it's necessary. Talk by Michael Green. Learn more about your ad choices. Visit megaphone.fm/adchoices

Explore how marijuana’s two main active compounds, THC and CBD, affect your brain and body, and what risk factors to watch out for. --In 1970, marijuana was classified as a schedule 1 drug in the United States: the strictest designation possible, meaning it was completely illegal and had no recognized medical uses. Today, marijuana’s therapeutic benefits are widely acknowledged, but a growing reco...

View full lesson: http://ed.ted.com/lessons/how-the-heart-actually-pumps-blood-edmond-huiFor most of history, scientists weren't quite sure why our hearts were beating or even what purpose they served. Eventually, we realized that these thumping organs serve the vital task of pumping clean blood throughout the body. But how? Edmond Hui investigates how it all works by taking a closer look at the h...

Practice more problem-solving at https://brilliant.org/TedEd/--You’re the chief advisor to an eccentric king who needs to declare his successor. He wants his heir to be good at arithmetic, lucky, and above all else, honest. So he’s devised a competition to test his children, and ordered you to choose the winner. The future of the kingdom is in your hands. Can you find the worthiest successor? Dan...

Take a look at the theories behind why earthquakes occur, what makes them so hard to predict and the warning system technologies we rely on today. --In 132 CE, Zhang Heng presented his latest invention: a large vase he claimed could tell them whenever an earthquake occurred for hundreds of miles. Today, we no longer rely on pots as warning systems, but earthquakes still offer challenges to those t...

Dig into how scientists are attempting to revive the functionally extinct northern white rhino through artificial reproduction.--In the savannahs of Kenya, two female northern white rhinos, Nájin and Fatu, munch contentedly on grass. They are the last two known northern white rhinos left on Earth. Their species is functionally extinct— without a male, they can’t reproduce. And yet, there’s still h...

View full lesson: http://ed.ted.com/lessons/why-does-ice-float-in-water-george-zaidan-and-charles-mortonWater is a special substance for several reasons, and you may have noticed an important one right in your cold drink: ice. Solid ice floats in liquid water, which isn't true for most substances. But why? George Zaidan and Charles Morton explain the science behind how how hydrogen bonds keep the...

View full lesson: http://ed.ted.com/lessons/the-cancer-gene-we-all-have-michael-windelspechtWithin every cell in our body, two copies of a tumor suppressor gene called BRCA1 are tasked with regulating the speed at which cells divide. Michael Windelspecht explains how these genes can sometimes mutate, making those cells less specialized and more likely to develop into cancer. Lesson by Michael Wind...

View full lesson: http://ed.ted.com/lessons/time-travel-and-einstein-s-special-relativity-colin-stuartTime travel is a staple of science fiction stories, but is it actually possible? It turns out nature does allow a way of bending time, an exciting possibility suggested by Albert Einstein when he discovered special relativity over one hundred years ago. Colin Stuart imagines where (or, when) this...

For some reason, says educator Al Vernacchio, the metaphors for talking about sex in the US all come from baseball -- scoring, getting to first base, etc. The problem is, this frames sex as a competition, with a winner and a loser. Instead, he suggests a new metaphor, one that's more about shared pleasure, discussion and agreement, fulfillment and enjoyment. Let's talk about ... pizza. Talk by Al...

Travel into the auditory system to explore the constant ringing sensation of tinnitus, why it happens and how to treat it. --Tinnitus has been bothering humanity since Ancient Babylon, plaguing everyone from Leonardo da Vinci to Charles Darwin. Today, roughly one in seven people worldwide experiences this auditory sensation. So what exactly is tinnitus, and where does this persistent sound come fr...

Check out the science of biohacking, where biologists go into a patient’s genetic code and reprogram their immune system to recognize and fight cancer cells.--The human body is made up of about 30 trillion cells that carry a code which has been duplicated over and over for billions of years - with varying degrees of accuracy. So what happens when the system breaks down and the machinery turns on i...

Get to know how a healthy marine ecosystem functions, and what creates the lethal conditions that lead to dead zones. --For most of the year, the Gulf of Mexico is teeming with marine life, from tiny crustaceans to massive whales. But every summer, disaster strikes. Around May, animals begin to flee the area. And soon, creatures that can’t swim or can’t swim fast enough begin to suffocate and die...

View full lesson: http://ed.ted.com/lessons/the-science-of-macaroni-salad-what-s-in-a-molecule-josh-kurzWhat do macaroni salad and gasoline have in common? They are made of exactly the same stuff -- specifically, the same atoms, just rearranged. So, while we put the former in our mouths and the latter in our cars, they are really just variations on the same atomic theme. Josh Kurz breaks macaroni...

Dig into the 800 year history and architecture of the Leaning Tower of Pisa and find out what gives the tower its infamous tilt. --In 1990, the Italian government enlisted top engineers to stabilize Pisa’s famous Leaning Tower. There’d been many attempts during its 800 year history, but computer models revealed the urgency of their situation. The tower would topple if it reached an angle of 5.44 d...

View full lesson: http://ed.ted.com/lessons/from-aaliyah-to-jay-z-captured-moments-in-hip-hop-history-jonathan-mannionJonathan Mannion once convinced rapper DMX to climb into a pool of blood -- all in pursuit of the perfect photo. In this passionate TEDYouth talk, the photographer shares how fighting for the moments he needs to capture has helped him tell the stories of Biggie, Jay-Z, Aaliyah and...