Sigourney Weaver reveals how she trained for her ‘Avatar’ role

Don’t call Sigourney Weaver an old lady.

In fact, the “Alien” actress turned back the clock 59 years to play 14-year-old Kiri in the long-awaited sequel “Avatar: The Way of Water.”

To convincingly portray a teenager — through the wonders of motion-capture technology — Weaver, 73, sat in on classes at New York’s famed La Guardia High School of Music & Art and Performing Arts. 

“I was just sitting on the side [of the classroom] listening to the pitch of the voices: everything from a childlike voice to an adult voice,” Weaver told USA Today about observing the young acting students. “I was just another actor. They had their own stuff to do.”

Na’vi alien Kiri is the daughter of Dr. Grace Augustine, Weaver’s scientist character who was killed in the original 2009 “Avatar.” Director and screenwriter James Cameron, who first worked with the three-time Oscar nominee on 1986’s “Aliens,” knew years ago — back in 2010 — that he wanted Weaver to go back to Pandora in a much younger role for the sequel.

“Even before [Cameron] wrote it, he said to me: ‘Nobody else knows this about you, but I know that you are 14 at heart, anyway. You’re so mature, and yet you’re always clowning around, so I have no doubt that you can do this.’”

Like the the rest of the “Avatar” cast, Weaver trained in breath-holding for the film’s aquatic scenes and even joined her younger co-stars in learning parkour for action sequences.

“I was determined to be able to do everything they did,” she said. “I didn’t want anyone to say, ‘She’s kind of an old lady.’ We all had to be really fit, and parkour is a very good way of getting there.”

Weaver enjoyed getting in touch with her inner child thanks to the time-machine magic of motion-capture technology. “It frees the actor from certain longtime conventions that you have to play your own age group,” Weaver said. “It just allows you to play anything and flow into any kind of form.”

And Weaver hopes that her teenage turn in “Avatar” — which opened atop the box office with $134 million this weekend — will strike a blow against ageism in Hollywood. “A lot of us older actors, the range of what we do is so extraordinary,” she said. “So I hope that Hollywood has gotten that message.”