There’s a reason why teenagers in movies and TV seem so, well, mature. The reason is that sometimes they’re being played by a much older actor — sometimes by a decade or more!

A good example is the cast of Grease. Although the film is a high school classic, there weren’t many actual high schoolers in it! Olivia Newton-John almost turned down the role because she thought she was “too old” to be playing a 16-year-old. Little did she know, 30-year-olds playing teens were a lot more common than she thought.

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Check out the video below that takes you through some notable teen roles that were, surprisingly, played by actors who were much older.

Although Olivia still looked young enough to play a teen at 29, she later revealed in 2017 that she felt a tad insecure playing the role.

“I worried that at 29 I was too old to play a high school girl,” she said. “But John [Travolta, who was 23 while shooting the film] was charming and really wanted me to do it, and that was one of the deciding factors. He’s a lovely man – we became great friends and he was very helpful to me on set, as I was not an experienced actress.”

Although Olivia said shooting the film was like being in school again, her favorite part about the role was when she got to shed her schoolgirl image and wear that iconic black catsuit.

“Everything about making the film was fun, but if I had to pick a favorite moment, it was the transformation from what I call Sandy one to Sandy two,” she said. “I got to play a different character and wear different clothes, and when I put on that tight black outfit to sing ‘You’re the One That I Want,’ I got a very different reaction from the guys on the set.”

We can bet!