Journalism school is expensive and of dubious utility. A degree from a top program can (maybe) help you get an entry-level job somewhere, but you’ll learn faster in a stint as a cops and courts reporter, digging up documents, talking to sources, and getting chewed out by your editor when you get a fact wrong. That calculus changes, though, if you don’t have an editor—if someone just props you up in front of a desk and expects you to knock out 10 blog posts, take a break for five minutes to eat a granola bar, and then knock out 10 more before you head home (where you will knock out 10 more blog posts). What do you do, then, if you think J-school’s a waste and you’re not getting any on-the-job mentoring?

You could do a whole lot worse than listening to the 12 episodes of Serial. It’s free, it’s entertaining, and it’s the best tutorial you’ll find on what it takes to be a reporter.

In the last episode of Slate’s Serial Spoiler Special podcast, David Haglund refers to Sarah Koenig’s series as “show-your-work journalism.” That’s the perfect term for Serial’s radical transparency. As Haglund points out, that transparency can be frustrating. Serial’s final episode got bogged down by a comically long discussion about whether a certain phone call could have been a “butt dial.” Koenig and her fellow producers talk about their fanatical effort to track down an old AT&T user agreement, which they finally uncover in a court filing that was part of a class-action suit that had nothing to do with Adnan Syed and Hae Min Lee. After all that, they find out that it could’ve been a butt dial, possibly.

The show is full of these kinds of reportorial rabbit holes. Some of them pay off—in Episode 1, Koenig succeeds in scoring an interview with a key witness named Asia McClain. Some of them don’t—Hae Min Lee’s family never agrees to speak to Koenig despite her attempts to contact them, attempts that she details exhaustively in Episode 9:

In my 20-plus years of reporting, I’ve never tried as hard to find anyone. Letters in English and in Korean, phone calls, social media, friends of friends of friends, two private detectives, Korean-speaking researchers, people knocking on doors in three different states, calls to South Korea. We never heard back from them. I learned a few days ago that they know what we’re doing; my best guess is they want no part of it, which I respect.

In a traditional piece of non-fiction, you don’t hear this stuff, and you don’t really miss it. In most cases, the narrative is more cohesive when you don’t show your work—when readers or listeners don’t know about the missed connections, the people who agree to talk to you but then back out, the protracted searches for facts that might not even matter.

Serial might have been more entertaining if these seams didn’t show, if Koenig and her crew crafted the series’ arc more carefully from the beginning and didn’t guide us down various cul-de-sacs. If you care about the nitty gritty of journalism, though, a tidier Serial would have been far less illuminating. A typical in-depth reporting project is a poker game where the writer keeps his cards hidden. Serial, by contrast, is the tutorial round, the one where everyone plays with their hands face up. I can say from experience, having spent a year trying to tell the story of the original “welfare queen,” that this is what the cards look like when you flip them over. This is how investigative journalism works.

Listening to Serial, you can glean specific bits of information about, say, how to unearth court records. But mostly, it’s instructive to hear Koenig and her crew putting in the work—knocking on Jay’s door to try to secure an interview, finding blueprints of the Best Buy to determine whether there was a payphone near the parking lot. As Allison Benedikt and Hanna Rosin noted in their initial report on the failings of Rolling Stone’s story on an alleged gang rape, Koenig did everything that Sabrina Rubin Erdely did not. On Serial, she is the standard bearer for due diligence, calling everyone, weighing (and re-weighing) every fact, and remaining conscious of her own biases. This kind of thoroughness—whether it’s foregrounded this conspicuously or not—is a journalist’s core obligation, especially on a story with such high stakes. Koenig fulfills it.

When Mike Pesca talked to Koenig a couple of months ago, he voiced his concern that the podcast would end up as “a contemplation on the nature of truth.” That’s not what Serial was. The show’s last episode, called “What We Know,” doesn’t posit that reality can shift depending on your perspective, or that there are some things in the world that are just unknowable. It’s telling that, rather than get all heady and metaphysical, Koenig and her fellow staffers spend most of the show weighing different pieces of evidence: the aforementioned (possible) butt dial, the fact that Jay knew where to find Hae’s car, the question of whether certain portions of the cellphone records did or didn’t match Jay’s story.

Koenig isn’t a philosopher. She’s a reporter. And at the end of “What We Know,” she offers the most important lesson any reporter can learn. “As much as I want to be sure, I am not,” she says. You have to know what you don’t know. Serial was an experiment in form. It could’ve been less confusing, more coherent. But if you view it as a documentary on a year inside a massively complex journalism project, then it was an unmitigated success. Listen to these 12 episodes, and you won’t know with certainty what happened to Hae Min Lee. You will know what it’s like to do the job of an investigative reporter, and to do it well.

Read more in Slate about Serial.