Before there were iPhones, iPads and the App Store, Apple was already serving up educational and instructional content on mobile devices to anyone who would listen.

Podcasts, which debuted 10 years ago this week, are more intellectually vibrant and commercially viable than ever. While the educational offerings, particularly for K-12, are not as aplenty as iOS applications, there are some longer-form gems for students, teachers, and anyone generally interested in educational issues.

In 2004, Podcasts were available to download from iTunes to play primarily on pre-touch generation iPods, Macs and PCs. Back then, users were required to sync their iPods to to a computer with iTunes in order to access individual programs or update their subscriptions. The best content came from repurposed programming from NPR and other terrestrial media providers, as well as pioneering web-based publications like Slate Magazine.

While NPR and Slate still shine on the podcast platform, today there are thousands of compelling audio and video podcasts available to download. If you have an iOS device, the pre-installed Podcasts app is the easiest way to wirelessly access all of this great content. Power listeners and/or those with Android devices can also discover and listen to Podcasts from several third party apps like Stitcher, BeyondPod, and DoggCatcher.

Most educational podcasts are accessible to anyone in middle school or older. History, language learning, and social science are the most compatible subjects to this format. And while many great Podcasts are also available as videos, our favorites merely require earbuds (and/or a speaker) along with a proper connection. Here are a few of the best free educational podcasts you can enjoy right now.

Lexicon Valley

Presented by Slate Magazine and hosted by media critic Bob Garfield and producer Mike Vuolo, Lexicon Valley looks at the etymology of a particular word or viral term. Recent episodes explore whether the word “orange” was first associated with a color or fruit, the rhetorical impact of demonstrative pronouns (“this”, “that”, “these” and “those”), and the hipster history of the term “dude”. Think of it as a modern audio iteration of William Sapphire’s classic On Language column in the New York Times Magazine. This podcast, which has new episodes about every two weeks, is great for high school students cultivating a love of language and anyone else who is curious about where some of our favorite words first appeared.

The Math Dude Quick and Dirty Tips to Make Math Easier

Speaking of dudes… This weekly podcast provides quick, accessible and entertaining explanations of common math terms and principals. Host Dr. Jason Marshall incorporates basic algebra problems into real world questions like “How is Rainfall Measured?” and quick tips on calculating how much one should tip. There are also wishful thinking questions that are quantified, like what are the chances of winning the lottery. This podcast is great for middle and early high school-aged students learning algebraic concepts, as well as older students preparing for standardized tests. Also recommended in the “Quick and Dirty” series is Grammar Girl.

Dan Carlin’s Hardcore History

If you have 15 or so hours to spare, you can become a scholar on historical topics as varied as World War I and the rise of Genghis Khan. Delivered by former radio and television commentator Dan Carlin, Hardcore History takes a deep and contrarian look at select events in world history. Carlin, who also hosts the popular Common Sense current events Podcast, embraces politics across the board and at one time simultaneously praised Ron Paul and Dennis Kucinich. Episodes of Hardcore typically last 3+ hours, and come out every two or three months. Basically, it takes him a year to fully explore any given subject or period.

K-12 Greatest Hits: The Best Ideas is Education

Geared towards teachers, parents and anyone interested in how educational technology is impacting learning in the classroom and beyond, this semi-regular podcast offers tips and inspiration from executive directors of leading education associations. Learn how to “flip” a classroom or how to combat high-tech cheating. The programs typically run 10 or 15 minutes, and cover a range of general education issues that are impacted by technology.

TEDTalks Education

Available as a video podcast but fully accessible without a screen, these are specially curated TED Talks where speakers address specific educational issues. New Talks that last between five and 25 minutes are added about two or three times per month. Some are specific to the future of education, while others explore grander topics like why the universe exists. The podcast, like everything else from TED, is recommended for high school-aged students and anyone else committed to lifelong learning.