As we get into our unit on stratification, we inevitably return to our old friends, the three sociological paradigms. How to structural functionalism, social conflict theory, and symbolic interactionism each think about stratification? How does ideology and help stratification reproduce itself? What did Marx and Weber have to say about all of this? And at the micro level, how does stratification work in everyday life?

In which John Green talks to about the future of Crash Course, which in this case is the past, because we're going to teach some more World History. This year, things will be a little more topical. We'll be talking about big ideas like money and debt, disease, and war. And Vikings.

In which John Green teaches you about World War II, and some of the causes behind the war. In a lot of ways, WWII was about resources, and especially about food. The expansionist aggression of both Germany and Japan were in a lot of ways about resources. There were other reasons, to be sure, but the idea that the Axis needed more food can't be ignored.

In which John Green teaches you about World War II, aka The Great Patriotic War, aka The Big One. So how did this war happen? And what does it mean? We've all learned the facts about World War II many times over, thanks to repeated classroom coverage, the History channel, and your grandfather (or maybe great-grandfather) showing you that Nazi bayonet he used to keep in his sock drawer and telling you a bunch of age-inappropriate stories about his harrowing war experiences. So, why did the Axis powers think forceful expansion was a good idea? (they were hungry). So why did this thing shake out in favor of the Allies? HInt: it has to do with the fact that it was a world war. Germany and Japan made some pretty serious strategic errors, such as invading Russia and attacking the United States, and those errors meant that pretty much the whole world was against them. So, find out how this worldwide alliance came together to stop the Axis expansion. All this, plus Canada finally gets the respectful treatment it deserves. Oh, and a warning: there are a few graphic images in this episode. Sensitive viewers may want to use caution, especially around the 9:15 mark.

Today we’re going to discuss the World Wide Web - not to be confused with the Internet, which is the underlying plumbing for the web as well as other networks. The World Wide Web is built on the foundation of simply linking pages to other pages with hyperlinks, but it is this massive interconnectedness that makes it so powerful. But before the web could become a thing, Tim Berners-Lee would need to invent the web browser at CERN, and search engines would need to be created to navigate these massive directories of information. By the mid 1990’s we will see the rise of Yahoo and Google and monolithic websites like Ebay and Amazon, forming the web we know today. But before we end our unit on the Internet we want to take a moment to discuss the implications of Net Neutrality, and its potential to shape the Internet's future.

The Crash Course Economics series is a great way to introduce concepts of Economics to students. The videos are short and easy to understand.

Today we’re going to talk about Bayes Theorem and Bayesian hypothesis testing. Bayesian methods like these are different from how we've been approaching statistics so far, because they allow us to update our beliefs as we gather new information - which is how we tend to think naturally about the world. And this can be a really powerful tool, since it allows us to incorporate both scientifically rigorous data AND our previous biases into our evolving opinions.

Hank tells us about the team of deadly ninja assassins that is tasked with protecting our bodies from all the bad guys that want to kill us - also known as our immune system.

Today we’re going to talk about how we compare things that aren’t exactly the same - or aren’t measured in the same way. For example, if you wanted to know if a 1200 on the SAT is better than the 25 on the ACT. For this, we need to standardize our data using z-scores - which allow us to make comparisons between two sets of data as long as they’re normally distributed. We’ll also talk about converting these scores to percentiles and discuss how percentiles, though valuable, don’t actually tell us how “extreme” our data really is.

This week, we're back in Europe to learn about Realism and Naturalism. In the 19th Century, playwrights like Eugene Scribe, Alexandre de Dumas Fils, and Emile Zola remade the French theater, first with Realism, and later with Naturalism. What are those things? Watch and learn.

Now that we’ve talked a little bit about how sociology works, it’s time to start exploring some of the ideas of the discipline’s founders. First up: Émile Durkheim. We’ll explain the concept of social facts and how Durkheim framed sociology as a science. We’ll introduce the idea of common consciousness and how Durkheim believed it binds society together. We’ll also talk about Durkheim’s studies on suicide and how he applied his concepts to a specific social problem.