A perfect fifth drives a textbook-worthy pre-chorus.

She's the pop lightning rod that just won't go away. And who am I to say that she must? I think part of her appeal is that no matter how much edge she tries to adopt or how much the tabloids follow her, she maintains a sort of squeaky clean image — a good girl caught up in tough situations! which is absolutely the front and center concept in this video — and puts out a lot of extremely inoffensive music. 

Which is not to say that she's not an effective songwriter; quite the opposite is true. She has a whole brand built on her waifish appearance and unpierceable country-girl sheen, but at the heart of it all, she knows what she's doing. For my money, "Trouble" is one of her more effective songs, with its half-time augmentation in the chorus, surprisingly effective incorporation of dubstep elements into an out & out pop song, and hook-laden pre-chorus. 

Intro: One of the most formidable recording artists of the last decade, Taylor Swift has won 10 Grammys, countless other awards (in the US, Canada, Australia, Germany, and the UK), and been inducted into the Nashville Songwriters' Hall of Fame. The song "I Knew You Were Trouble" was released on the artist's 2012 album Red, which garnered five Grammy nominations over the course of two years. "Trouble" peaked at no. 2 on the Billboard Hot 100 (and at the same spot in Israel & Scotland) and hit no. 1 in Canada. Swift wrote the song alongside legendary Swedish hitmakers Max Martin & Shellback.

Analysis: Yes, that notorious interval is a perfect fifth (although it's not "do-sol" within the context of the key). First heard in the pre-chorus section of the song at 2:44 in the above video recording (there is an extensive video prologue to the song in Swift's official video, so the pre-chorus is heard about 40 seconds into the song), the perfect fifth is heard between the words "I knew" (and "you were"). In part because Swift sings the remainder of the song in step-wise melody, and because the instrumentation & beat subdivision changes at the pre-chorus, this particular interval is notable.

Considerations for Teaching: Like most of Swift's ouvre, this song contains no offensive language or material. The video shows a couple kissing close and lying in a bed, but otherwise is in no way unteachable.