Season 3 of summer school is here asking the biggest economic questions about what makes an entire economy grow or contract. Episode 1 begins with the rise of macroeconomics as a field, with one of the great economic debates of the 20th century: what causes booms and busts, and what can the government do about it? How free should a free market be? It's a debate (over beats and with an actual rap battle) between John Maynard Keynes and F.A. Hayek. Watch this Tik Tok to learn more and listen to...

In the last class of Planet Money Summer School Season 2, we cover one more important market — cryptocurrency. If you're thinking about investing in crypto, do you know exactly what it is that you're buying? Or how it should (if at all) fit alongside the rest of your investments? | Subscribe to our weekly newsletter here and take don't forget to take the Summer School Final Quiz.

Investing during a bubble can leave you bust. But how to tell the difference between a bubble before it bursts and an investing rocket ship taking off? We'll run through a historical example and look inside our own thinking to find the mental biases that can contribute or exacerbate bad bubble thinking. | Subscribe to our weekly newsletter here.

A few years back, Cardiff asked for an unusual Christmas present: a junk bond... Parallel to the stock market, the bond market offers different levels of risk and reward. In this class, what is a bond, how do they differ from stocks, and how do they help companies grow? | Subscribe to our weekly newsletter here.

Even if you don't own stocks, there are a lot of reasons to care about investing. We meet some of the folks left out of the stock market who deploy sophisticated economic thinking, even creating their own alternate financial systems. Our professors help us understand how consumption smoothing and life-cycle theory apply to personal finance. And we meet the creator of the 401(k).

In 2006, Warren Buffett bet a million dollars that the most brainless, boring investment around would do better than the researched, handpicked investments of some of the smartest hedge fund managers in the world. The second class of Summer School looks at how that bet played out, the origins of the index fund, and why it's so hard to beat the market. Returning to the underlying theme of risk and reward, we also discuss how diversification reduces risk.

The first class of Planet Money Summer School starts off with a field trip. With the help of a cow, two economists, and three cute animals, we learn what a stock is and how stocks are priced, and we begin to see the psychological forces that make prices move up and down on the stock market. Keep an eye out throughout for our big theme for the course this summer: risk and reward.

Summer School graduates take the stage to show us how we can all see our everyday world through the beautiful lens of economics. | Take the final exam and get your diploma here.

Inside one insurance policy is a world of incentives and bad behaviors. Take the final exam and get your diploma here.

A Black ad executive figures out how to reach diverse audiences.

The surprisingly entertaining history of the income tax. | Subscribe to our weekly newsletter here.

The economics of free trade and what happens when governments get involved. | Subscribe to our weekly newsletter here.

Class 4 brings us an economic conundrum: how do you efficiently share a scarce resource? | Subscribe to our weekly newsletter here.

In our third class, we take all that we've learned about decisions and markets and bring it to a former drug kingpin. | Subscribe to our weekly newsletter here.

In our second class, we meet our old friends supply and demand and do graphs using only the power of the human voice. Then, we show you how markets can be created anywhere by telling the story of a food bank that had too many pickles and not enough pancake syrup. It's economics to the rescue. | Subscribe to our weekly newsletter here.

First lesson: Economics is not about money. It's a lens of great power and beauty. In this episode, we meet our teachers and learn the first four fundamental concepts of economic thinking, and watch them applied to things like dating and hailing a cab. | Subscribe to our weekly newsletter here.

Planet Money Summer School is a crash course in economics for your ears.