Hank gives a quick run-down of the reasons scientists think the land mammals of today are nowhere near the size of the largest sauropods. Some of them might surprise you!

If you get most of your information about ancient animals from vintage cartoons or action figures, then a lot of things that you think of as "dinosaurs" actually weren't. Learn about the definition of true dinosaurs and the evolutionary...

The Apollo 11 mission had many opportunities for things to go awry, and they almost did! Find out how a felt-tipped pen may have saved the lives of the first astronauts on the moon, and more!

Before the world of humans began, there was the world of the gods. Four brothers wandered this celestial realm. One day, the brothers snuck into a spirit's house and spotted a giant gourd hanging in the corner. But as they tried to look...

A white, puffy dress. Eternal love. A joint tax return. Marriage means something different to everyone and has changed over time and across cultures. Alex Gendler traces the history of getting hitched, providing insights on polygamy,...

Maybe you'd like to just hear about one topic for a while. We understand. So today, let's just watch some videos about Gravity. We'll learn about why we don't fly off into space, what mass has to do with it, how does air resistance work,...

Scientists overwhelmingly agree that our climate is changing, Earth is getting warmer, sea levels are rising, and it's primarily because of humans putting lots of carbon dioxide in the atmosphere. Whether you already trust in the...

Oceanographer John Delaney is leading the team that is building an underwater network of high-def cameras and sensors that will turn our ocean into a global interactive lab -- sparking an explosion of rich data about the world below.

There’s a reason behind the saying “fish out water.” Fish don’t tend to do well if they’re not immersed in liquid. But walking catfish are surprisingly adept at making their way on land.

In this video, we'll learn about the life story of journalist, orator, teacher, suffragette, and anti-lynching activist Ida B. Wells-Barnett. Ida B. Wells made her name writing and speaking and working to improve the lives of Black...

In 1903, US President Theodore Roosevelt took a camping trip in California's Yosemite Valley with conservationist John Muir. Roosevelt famously loved the outdoors, but Muir had invited him for more than just camping: Yosemite was in...

Want to learn more about the topic in this week's video? Here are some key words/phrases to get your googling started:

- extreme weather - Conditions and events that occur with low frequency, but which often have significant...

Why is my weather app sometimes wrong? Well it has a lot to do with wind. Jet Streams, air cells, the shape and movement of the Earth... there are a lot of things that make weather a little unpredictable. In this episode of Crash Course...

Earth's ocean water is continuous. How can we divide it into sections that are more useful?

Aboard Mission Blue, scientist Greg Stone tells the story of how he helped the Republic of Kiribati to create an enormous protected area in the middle of the Pacific -- protecting fish, sealife and perhaps the island nation itself.

Professor Fukan_, 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...

In cities, evolution occurs constantly, as countless plants, animals and insects adapt to human-made habitats in spectacular ways. Evolutionary biologist Menno Schilthuizen calls on peculiar beings such as fast food-loving mice and...

In which John Green teaches you about the (English) colonies in what is now the United States. He covers the first permanent English colony at Jamestown, Virginia, the various theocracies in Massachusetts, the feudal kingdom in Maryland,...

For smallholder farmers in India, agriculture has long been an unreliable source of income -- crops that flourish one season can fail the next, thanks to heat, pests and disease. But climate risk is now making the profession nearly...

We may never know when our ancestors walked out of the water into dry land. But it's possible they may have been walking in water for millions of years!

Should your driverless car kill you if it means saving five pedestrians? In this primer on the social dilemmas of driverless cars, Iyad Rahwan explores how the technology will challenge our morality and explains his work collecting data...

Scientists have long known that cows are a huge source of the greenhouse gas methane, contributing up to four percent of emissions globally. But could there be a way to make cattle less -- ahem -- gassy? Animal scientist Ermias Kebreab...

Welcome to the romantic, violent, treacherous, and murderous mating lives of bugs.

We need to care for and live in harmony with the environment, says climate and gender activist Ernestine Leikeki Sevidzem. The best way to do that? Nurture a forest generation: one that learns to protect nature. Sevidzem shares how she's...