In which John Green investigates the dawn of human civilization. John looks into how people gave up hunting and gathering to become agriculturalists, and how that change has influenced the world we live in today. Also, there are some...

On the 4th of July, Americans like to celebrate the things that make the United States unique, and a lot of those things have to do with our geography. That remarkable geography is also responsible for some pretty unique weather, and...

If we want to establish a colony on the Moon, coming up with enough water is a huge challenge. Scientists have long suspected there might be water hiding on the lunar surface. Were they right? Plus, some quick recovery work led to...

Get to know plasma, the most common, but probably least understood, phase of matter in the universe!

Stars blowing up is a surprisingly common occurrence, but who would have thought to search the bottom of the ocean if you were trying to study them?!

The human body is a complicated thing! To be able to move, fight off diseases, and even see colors, lots of different systems and organs need to work together. Squeaks' robot body is pretty complicated, too, so Jessi has put together a...

So, how are people fixing their water problems? In this episode of Crash Course Kids, Sabrina talks about a few different examples how some freshwater sources were good, then bad, then made good again. Also, Sabrina talks about...

In this video Paul Andersen explains how the gravitational field strength is directly related to the mass of the object and indirectly related to the square of the distance from the center of mass. The equation for gravitational field...

Two linemen colliding can light a 60W bulb for over a minute!

Is the universe expanding? About a hundred years ago astronomers made a discovery that helped us unravel the mystery of the history of the universe!

Some animals have a special kind of fat below their skin to stay warm in the chilly months. Follow along with this special experiment to learn more about how blubber works!

At the beginning of the Triassic Period, with the continents locked together from pole-to-pole in the supercontinent of Pangea, the world is hot, flat, and very, very dry. But then 234 million years ago, the climate suddenly changed for...

In this video Paul Andersen explains how the chloroplast in plants harnesses power from the Sun to form high energy molecules like glucose. The structure of a chloroplast as well as a brief discussion of the light reaction and Calvin...

It's 1762 BCE. As dawn breaks in the Babylonian city of Sippar, Beltani— a priestess and businesswoman— receives an urgent visit from her brother. He makes a troubling accusation: her tavern keeper has been undermining the business...

Humans have an almost insatiable energy demand, so scientists and engineers are always on the lookout for sustainable ways to provide the energy we need. And some of these ideas go way beyond solar panels and wind...

In 2018, a single power plant produced more energy than the world's largest coal-powered and gas-powered plants combined. China's Three Gorges Dam relies on running water, and is capable of producing more energy than any other power...

Activist Shad Begum has spent her life empowering women to live up to their full potential. In a personal talk, she shares her determined struggle to improve the lives of women in her deeply religious and conservative community in...

Everyone is familiar with Twitter, the uber-popular micro-blogging site, which limits the user to 140 characters. The tweet is perfect for sharing your favorite links and updating the world about your life, but it might also be the...

Which Came First - The Rain or the Rainforest

So it's February 29th and we have 366 days this year instead of 365- what's the deal with Leap Years?

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...

Today Hank wraps up our look at Connective Tissues with a discussion of its various types and a breakdown of what you can and can't easily break down. Also chicken.
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As engineer, sometimes lives will be in your hands, so this week we’re exploring safety and its impact on engineering. We’ll discuss the difference between occupational safety and public safety and how to analyze and review a process for...

We've reached the grand finale of our four part series on human reproduction: BABIES! Today Hank walks you through the stages of pregnancy, beginning with how a zygote develops into blastomeres to a morula to a blastocyst and finally to...