"Class" has its US premiere Saturday, April 15th on BBC America at 10:10 p.m. ET/PT and 9:10 p.m. CT. This review, originally published on October 22nd for the show's UK release, has been updated to get you ready for the new "Doctor Who" spin-off show.

Right, pay attention, class!

Today's assignment is "Class", a new drama pitting teenagers against aliens. Right -- tuck your shirt in, and we'll begin!

You don't need to have done your homework on the long-running sci-fi show "Doctor Who" to understand this new spin-off. "Who" star Peter Capaldi drops by the opening episode to give "Class" a stamp of approval, but it's a very different show to its family-friendly parent.

Oi -- are you chewing?

"Class" is set at Coal Hill, an East London school glimpsed in the opening episode of "Who" in 1963 and occasionally re-appearing right up until the latest season, when companion Clara worked there. Now it's a modern academy and the site of a rift in time and space, through which all manner of alien threats turn up.

Created and written by Patrick Ness, the show owes a debt to other teens-vs-monsters-that-are-also-metaphors-for-growing-up shows like "Buffy the Vampire Slayer" and "The Vampire Diaries". And as in those shows, pop culture self-awareness is one of the essential elements, which means "Class" name-checks its influences -- and because the Hellmouth is taken, the team consider calling their rift "the bunghole".

Excuse me, would you care to share what's so funny with the rest of the class?

The cast comes full of Tumblr-ready ship-worthy characters. The team of timey-wimey teens includes Vivian Oparah as Tanya, the youngest but smartest; Sophie Hopkins as April, who doesn't want to be the nice one but kind of is; and Charlie, who definitely isn't from Sheffield.

The standout is smouldering Fady Elsayed as the cocky but conflicted Ram. Meanwhile Katherine Kelly chews the scenery as vampy teacher Miss Quill.

"Class" opens with the kids taking on deadly shadows, which feels like a hangover from a previous "Who" episode. But like previous "Who" spin-off "Torchwood", ambiguous characters, splashy gore and the odd rude word give it its own feel.

Er, excuse me -- language!

One thing the show wobbles on is how much the other kids are aware of the weirdness around them, something "Buffy" deliberately pushed to one side right up to the emotional prom episode. "Class" opens with the cringe-worthy line "Everyone knows kids in this school go missing", and it remains to be seen how the show will strike the balance between the weird and the everyday. Must try harder!

Wait -- the bell is for me, not for you! The first two episodes, "For Tonight We Might Die" and "The Coach with the Dragon Tattoo", are available to watch online on BBC iPlayer from Saturday 22 October. It will then be shown on BBC One in the UK, ABC in Australia and BBC America in the US in 2017. Here's how you can see it around the world.

Right -- you may go. No running in the corridor! I said -- oh forget it.

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