Hank introduces us to biogeochemical cycles by describing his two favorites: carbon and water. The hydrologic cycle describes how water moves on, above, and below the surface of the Earth, driven by energy supplied by the sun and wind. The carbon cycle does the same... for carbon!

Chapters:
1) Hydrologic Cycle
A) Clouds
B) Runoff
C) Oceans
D) Evapotranspiration

2) Carbon Cycle -
A) Plants -
B) Fossil Fuels -
C) Oceans -
D) Global Warming -

In which Stan Muller talks about some of the problems in Intellectual Property law as it exists today. He'll also teach you a little about how IP law applies to everyone's favorite media platform, YouTube. Lastly, he'll do a little prognosticating, and try to predict how IP law might change in the future.

It’s time for molecular analysis! On this episode of Crash Course Organic Chemistry, we’re learning about mass spectrometry and infrared spectroscopy through the lens of a forensic investigation. Put on your lab coats, and let’s solve this mystery!

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 Americans. She wrote for a number of outlets, and covered a wide array of issues.

Gases are everywhere, and this is good news and bad news for chemists. The good news: when they are behaving themselves, it's extremely easy to describe their behavior theoretically, experimentally, and mathematically. The bad news is they almost never behave themselves.
In this episode of Crash Course Chemistry, Hank tells how the work of some amazing thinkers combined to produce the Ideal Gas Law, how none of those people were Robert Boyle, and how the ideal gas equation allows you to find out pressure, volume, temperature, or number of moles. You'll also get a quick introduction to a few jargon-y phrases to help you sound like you know what you're talking about.

Chapters:
Ideal Gas Law Equation
Everyone But Robert Boyle
Ideal Gas Law to Figure Out Things
Jargon Fun Time

We don't live in a perfect world, and neither do gases - it would be great if their particles always fulfilled the assumptions of the ideal gas law, and we could use PV=nRT to get the right answer every time. Unfortunately, the ideal gas law (like our culture) has unrealistic expectations when it comes to size and attraction: it assumes that particles do not have size at all and that they never attract each other. So the ideal gas "law" often becomes little more than the ideal gas estimate when it comes to what gases do naturally. But it's a close enough estimate in enough situations that it's very valuable to know. In this episode, Hank goes through a bunch of calculations according to the ideal gas law so you can get familiar with it.

Chapters:
Large Size + Attraction to Others
Mendeleev to the Rescue
The Hindenburg Disaster
Helium vs. Hydrogen
Making Fire with Cotton and Your Fist

In which John Green teaches you about Chinua Achebe's 1958 novel, Things Fall Apart. You'll learn about Igboland, a region in modern-day Nigeria, prior to the arrival of the British Empire. Achebe tells the story of Okonkwo, an Igbo villager who has worked his way up from life as a sharecropped and become a respected leader in his community. Okonkwo has a tragic fall and is exiled. And then the trouble starts. British missionaries arrive and change everything. Things Fall Apart has a lot to say about colonization and even something to say about decolonization.

Our final episodes of Anatomy & Physiology explore the way your body keeps all that complex, intricate stuff alive and healthy -- your immune system. The immune system’s responses begin with physical barriers like skin and mucous membranes, and when they’re not enough, there are phagocytes -- the neutrophils and macrophages. It also features the awesomely named natural killer cells and the inflammatory response, and we'll explain how all of these elements work together to save the day if you happen to slip on a banana peel.

Chapters:
Introduction: Immune System
Skin as a Physical Barrier
Mucous Membranes
Phagocytes: Neutrophils and Macrophages
Natural Killer Cells
Inflammatory Response
Review

In the penultimate episode of Crash Course Anatomy & Physiology, Hank explains your adaptive immune system. The adaptive immune system's humoral response guards extracellular terrain against pathogens. Hank also explains B cells, antibodies, and how vaccines work.

Chapters:
Introduction: Adaptive Immune Responses
How B Cells Identify Antigens
B Cells Become Effector Cells & Memory Cells
How Antibodies Fight Antigens
Active and Passive Humoral Immunity
How Vaccines Work
Review

THE FINAL SHOWDOWN! This is the last episode on the immune system and also the very last episode of Crash Course Anatomy & Physiology. In it, Hank explains how the cellular immune response uses helper, cytotoxic, and regulatory T cells to attack body cells compromised by pathogens. He also explores how cytokines activate B and T cells, and what happens if your immune system goes rogue and starts causing autoimmune trouble.

Chapters:
Introduction: Cells Fight Cells
Professional Antigen Presenting Cells
Helper T Cells
Cytotoxic T Cells
Immunodeficiencies
Autoimmune Disorders
Review

This week we are building on last week’s outline of American stratification to explore how class differences affect people’s daily lives. We’ll explore variations in everything from values & beliefs to health outcomes, and look at how these things can perpetuate inequality across generations.

In which John Green teaches you about European Imperialism in the 19th century. European powers started to create colonial empires way back in the 16th century, but businesses really took off in the 19th century, especially in Asia and Africa. During the 1800s, European powers carved out spheres of influence in China, India, and pretty much all of Africa. While all of the major (and some minor) powers in Europe participated in this new imperialism, England was by far the most dominant, once able to claim that the "sun never set on the British Empire." Also, they went to war for the right to continue to sell opium to the people of China. Twice. John will teach you how these empires managed to leverage the advances of the Industrial Revolution to build vast, wealth-generating empires. As it turns out, improved medicine, steam engines, and better guns were crucial in the 19th-century conquests. Also, the willingness to exploit and abuse the people and resources of so-called "primitive" nations was very helpful in the whole enterprise.

Chapters:
Introduction
Opium in China
The Treaty of Nanjing and British Control of Hong Kong
The Scramble for Africa
Why Europeans Previously Failed to Conquer Africa
How Technology Enabled European Colonization of Africa
An Open Letter to Hiram Maxim
African Resistance to European Invasion
European Domination Through Indirect Rule
Why Native Rulers Cooperated with Indirect Rule
Native Resistance to Imperialism Around the World
Khedive Ismail of Egypt & Business Imperialism
Credits

Art tells the story of humanity across societies and cultures, but keeping that art around for future generations can be a monumental task. In this episode of Crash Course Art History, we’ll learn how art historians preserve, restore, and conserve art that tells the story of who we are and who we want to be.
Chapters:
Introduction: "The Last Supper"
Preservation
Restoration
"Ecce Homo"
Conservation
Review & Credits
Credits

What is a trade deficit? Well, it all has to do with imports and exports and, well, trade. This week Jacob and Adriene walk you through the basics of imports, exports, and exchange. So, you remember the specialization and trade thing, right? So, that leads to imports and exports. Economically, in the aggregate, this is usually a good thing. Globalization and free trade do tend to increase overall wealth. But not everybody wins.

Hank describes how cells regulate their contents and communicate with one another via mechanisms within the cell membrane.

Chapters:
1) Passive Transport
2) Diffusion
3) Osmosis
4) Channel Proteins
5) Active Transport
6) ATP
7) Transport Proteins
8) Biolography
9) Vesicular Transport
10) Exocytosis
11) Endocytosis
12) Phagocytosis
13) Pinocytosis
14) Receptor-Mediated Endocytosis

Inequality is a big, big subject. There's racial inequality, gender inequality, and lots and lots of other kinds of inequality. This is Econ, so we're going to talk about wealth inequality and income inequality. There's no question that economic inequality is real. But there is disagreement as to whether income inequality is a problem, and what can or should be done about it.

You might have recognized the names of some of the Greek natural philosophers. They were individuals with quirky theories, and we have records about them. But they weren’t the only people making knowledge back in the day. Today, Hank takes us to India to talk Vedas, Maurya Empires, and some really good doctoring.

In which Mike Rugnetta continues our unit on pantheons with the complex Indian pantheon, focusing on stories that were written in Sanskrit. We start with a violent creation story. We talk about the concept of Brahman, and the personification as three deities: Brahma, Vishnu, and Shiva. Then, the goddess Durga teaches us how to behead a buffalo demon while riding a lion.

Today we conclude our unit on Philosophy of Religion and Hank gets a little help from Indiana Jones to explain religious pragmatism and Pascal’s Wager, fideism, and Kierkegaard’s leap to faith.

In this episode of Crash Course Physics, Megneto helps Shini explain what induction is, how it works, and why magnetism is so seemingly complicated.