Describe Aliens in the Attic for us?

It’s great fun and there’s something in it for everyone. It’s about a family being invaded by aliens – except just the kids know. I play the older sister, Bethany, who is distracted and madly in love with her new boyfriend. She’s in a teenage love bubble but she eventually wakes up to joins forces with her younger siblings to… I’m not going to ruin the ending! It’s shot in the same vein as kids’ classics, like The Goonies – the best kids’ film of all time.

 What would you do if you found aliens in your own attic?

I’d be freaked out! Like Bethany I need to be in control. When she finds out what’s happening, it’s the first time in her life that she doesn’t know what to do. I’m the same. We share that controlling thing. I can’t cope if something comes out of nowhere at me.

 How else are you like Bethany?

She’s the older sister and I was the baby of our family, so I don’t know about that. But when I was younger I did used to go boy crazy like she does. When I was with someone, he was all that mattered. Thankfully I’ve grown up a bit. I’m so different now I’m nearly 24!

 Did you end up loving the aliens?

Yes, I loved them. They are adorable. Well, at the beginning they are a bit ET, cute, come up to my knees and we all hang out. But by the end they go all King Kong and scary.

 Did you have fun making the film?

Yes. The cast were awesome and because we shot in New Zealand it was like making a movie on vacation. Every weekend we all hung out and went to the beach.

 Did you have a favourite moment
on set?

There were so many great moments and I never managed to keep a straight face. Off-camera we were all singing non-stop musical numbers; entertaining the younger kids. Ashley (Boettcher who plays Hannah Pearson) was so impressed she printed off the lyrics to Rock Star by Hannah Montana and forced me to sing it to her. Constantly.

 After High School Musical are you mobbed by children everywhere you go and asked to sing?
I live in LA and people are used to seeing celebrities so fans usually just ask for an autograph. But when I perform, it’s a different story. I sang at a shopping centre a couple of days ago, to 1,000 people, then afterwards the fans went crazy. But I wouldn’t be here without fans, so I’m very thankful.

 Have you become a role model?
Apparently. Vanessa Hudgens and I were at the American Music Awards, freaking out because we were sitting next to Celine Dion and she turned to me and thanked me so much for being a role model for her son! And I had always looked up to her! I don’t see myself as that to be honest because no-one is perfect. But when kids say it I feel it’s really cool because I never try to be anything other than myself.

 Was it a relief not to be breaking into song every five minutes for this film?

Aliens was different, yes, but I’ve loved doing both. And there were similarities. There was lots of CGI in this and I found that doing those scenes was exactly like learning the choreography for High School Musical; how to move around and interact with aliens when they weren’t really there.

 What’s next for you?

I’m promoting my new album. Life is crazy. Non stop. What’s exhausting is the flying. That, and the time differences take it out of you. But I love what I do and I have a great team around me. They’re like family.

 What keeps you grounded?

My stuffed penguin. He comes everywhere with me! No, that’s true but it’s my family really. We speak all the time and they don’t let me get a big head. My parents sent me to a regular high school, I had a normal childhood, worked in a clothing store as a teenager. And that upbringing has made me even more grateful for what I have.

Aliens in the Attic is out on DVD and Blu-ray from 1 February