Like 17-year-olds here and across the pond, Freddie Highmore has been polishing his college application essay.

Unlike others, he's been doing it while focusing on studies for two math classes (regular and something decidedly English called "further math") along with French and Spanish and promoting "Astro Boy."

In the animated movie opening today, he speaks for two characters, a young brainiac named Toby who dies in an accident and Astro Boy, the look-alike robot given Toby's memories and a power source made of positive "blue" energy.

Highmore, who played distinctively different twins in "The Spiderwick Chronicles," spoke for a "daemon" in "The Golden Compass" and was part of the voice talent in "Arthur and the Invisibles," says there is no single secret to success in the recording booth.

"I think that it's important not to be self-conscious at all, that's the main thing. Forgetting about people who might be watching you, technicians might be laughing at you if you're jumping up and down to get out of breath," is essential, he said in a phone call this week.

"But at the end of the day, you want to create the best finished character as you can."

Highmore is a master at that. In "Finding Neverland," he broke moviegoers' hearts as a child who lost his father and watches his mother's health fade away, while he thrilled and touched fans as a kind-hearted boy who finds a golden ticket in "Charlie and the Chocolate Factory."

Those movies teamed Highmore with Johnny Depp, and he shared a character with Russell Crowe in "A Good Year." He had to learn an American accent and how to play the guitar and organ and conduct an orchestra for "August Rush" opposite Robin Williams.

So it's no wonder that the seemingly serious Highmore engages in a bit of tomfoolery with strangers who say, "I know you from somewhere," but they're just not sure where.

"It's quite a fun game -- they always go through these lists of, 'Do you go to the library?' or 'Are you at my local skateboard park?' or whatever. No, no, you just sort of let it go on for a while."

As typically happens with animated movies, Highmore recorded his lines in London separate from other performers although director David Bowers was always there.

"That made a load of difference because first of all, he knew what everyone else was doing and could relate that to me and he knew how the scenes were going, how they were working out, how they were being put together and so he could orchestrate everyone to be on the same page."

Highmore had the benefit of cardboard cutouts and intricately designed books as visual aids. Even better, though, a camera recording his facial expressions and mouth movements allowed the artists to match their animation to his voice instead of the other way around.

Highmore wasn't familiar with Astro Boy although he got up to speed with the manga or Japanese comic book.

Astro Boy debuted in 1951 as a character in Osamu Tezuka's manga. In 1963, he appeared in a black-and-white TV series produced in Japan and then aired in the United States. Astro Boy also was the focus of a 1980 TV series and an update that debuted in 2003.

"It was nice to be able to discover him, really, and that was sort of a joy itself but also, the fact that so many people haven't had an experience with Astro Boy yet made it quite an exciting thing to be working on. It was like we were all in on this huge secret, this fantastic character that he is, and then we're going to sort of reveal it to everyone now."

Astro Boy, Highmore says, is "considered the Japanese Mickey Mouse for over 50 years now, so there's got to be something special about him, too, to make him so well loved over there."

Highmore, who expects some of the jokes and emotional moments will play differently for adults and children, says it was important not to make the pint-size superhero too robotic.

"Obviously, Toby is a human but Astro Boy as well has the heart of a human, he's got the soul of a human being and it was important to make sure that the film sort of stayed grounded and could be accessible to everyone, that the main character is someone who could be related to."

"Astro Boy" didn't disrupt Highmore's schooling since he could do the voice work after class or on weekends. When he travels, he has a tutor and assignments from school that allow him to keep pace with his classmates. He's considering pursuing languages in college, perhaps sticking with Spanish and starting another from scratch.

Highmore, who earlier this year shot the apartheid-era "Master Harold ... and the Boys," has said he might not continue acting as an adult.

Asked if he still feels that way, he said, "I'm not totally set on doing acting. I'm still open to other avenues in terms of a future career and I'm definitely going to go off to university so I've got the chance to do something else if I want to.

"I think that acting's fantastic at the moment and I've always thought there'd be a time where I'd had enough of it and thought that it was something that had been great fun and now it was time to move on, but that moment hasn't happened yet."

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