I’ve been waiting for the new season of Relatively Prime for more than three years. I’ve listened to *Chinook*, the highlight of Season 1, countless times since then. And finally, finally, it’s arrived in my podcast feed.

Woo, and for that matter, hoo!

Mathematical broadcaster extraordinaire, podcasting legend, and Abel Prize nominee *(in his dreams – Ed.)* Samuel Hansen begins the new season with a sly tip of the hat both to his old podcast and to its excellent nearly-replacement, by talking to linguist Lynne Murphy to try to settle the century-old trans-Atlantic dispute over ‘math’/’maths’. Naturally, Samuel’s conclusion is wrong – but useful. What can you expect from the only country that refuses to call a game where a ball-shaped object is propelled mainly by the feet “football”?

He’s on firmer ground when he interviews Anthony Lo Bello about the origin of mathematical words, apparently the only dictionary Samuel has read cover to cover, finding out the origin and meaning of words such as hypothesis (directly from Greek), algebra (by way of transliterated Arabic) and combinatorics (which Lo Bello doesn’t *quite* call a mongrel, but you can tell he wants to). They also talk about the origin of *sine*, which originated in Sanskrit and came to English via Arabic and Latin — but mysteriously, they don’t say what it originally meant, so that was a bit of a bust. Otherwise, a fascinating segment.

The Lexicon’s third story leaves words behind in favour of symbols, which are a surprisingly recent mathematical development. Samuel’s interviewee, Joseph Mazur, starts by defining what a symbol is (a representation of a thing that doesn’t look like the thing represented — so an **O** used to represent a circle isn’t a symbol) and talks about the difficulties of developing and standardising notation without sending Samuel off on a Newton/Leibniz rant, possibly the most remarkable thing about this episode.

As a mathematician with an interest in education, the penultimate segment was the one that caught my ear: Tharanga Wijetunga and Kirthi Premadasa have been looking at how to make word problems more engaging and memorable — no Hannah’s sweets for them! They’ve categorised word problems into several different classes and found that ones that resonate with things students care about stick much better than ones about things other people can or should do. I’d have liked to hear an explanation of exactly what “I” “R” and “U”-type problems were, but found the idea intriguing all the same.

Lastly, Samuel speaks with Tim Chartier, someone I follow on Twitter largely because of his sports analytics work. Apparently, he’s also a trained mime, and travels the world demonstrating mathematics without words. This rather typifies Samuel’s approach to podcasting: he’s not afraid to try something that sounds like an absurd idea for an audio segment, and then, astonishingly, pull it off.

*The Lexicon* is a very solid start to Season 2 — similar in feel to *This American Life*, with high quality interviewees and a strong thread running through the show. I’m looking forward to the remaining seven episodes with some anticipation; my main question is whether he can top *Chinook*.

### More information

**Listen** to Relatively Prime: The Lexicon at relprime.com. While you’re there, catch up on Season 1.

*Colin was given early access to Season 2 of Relatively Prime, in return for writing reviews of each episode. Furthermore, Samuel is Aperiodipal numero uno and most of us chipped some money into the Relatively Prime Kickstarter, too. Just so you know.*