By JOSEPH DIAZ

Alaina Clifford, 18, has dreams that extend way beyond the Pine Ridge Reservation where she has lived all her life. She is a cheerleader and a gifted performer starring in the many school plays including Charlotte’s Web.

Her biggest talent is her voice. Last year, Alaina was chosen to sing the national anthem at a South Dakota state boys basketball championship. Alaina has a long-time ambition of being on “American Idol.”

“Alaina has always said, ‘I don’t want to have kids, I’m going to be a singer. I’m going to be a star!’” recalls her mother, Julie.

Alaina and Montana at prom. (Credit: Julie Cuny)

She is a lot like her mother Julie, who dreamed of traveling the world before she got pregnant. Now Julie works as the manager of an elementary school cafeteria. “When you become a mother your passion and dreams change,” she says.

Alaina says six of her high school classmates are pregnant.  Teen birthrate on the reservation is three times the national average. But Alaina is determined to be different. Even her boyfriend, Montana, is a star, receiving the prestigious Gates scholarship for college and attending South Dakota State University.

But just a few months after Alaina and Montana begin dating, she finds out she is pregnant.

“Oh crap!” is Julie’s reaction when she hears the news. “I was a little disappointed, but I didn’t want to her know I was disappointed.”

Alaina and Montana get married and in the middle of her senior year of high school Alaina gives birth to baby Payson.

“Last year my biggest worry was if I was going to get to go to the basketball game, or what part I got in one-act plays. It’s hard to think that those were my biggest worries,” she says.

But there is something in Alaina that won’t give up. Although half of her class has already dropped out, she studies hard and graduates, holding her son as she accepts her diploma.

“You can’t change the past, but you can make the future better!” she says.

Alaina also doesn’t give up on her “American Idol” dreams. She auditions for the show with the song, “I’m Going Down” by Mary J. Blige.

Learn more about Alaina and the challenges she and other Pine Ridge children — like Robert Looks Twice — face Friday at 10 p.m. ET on “Hidden America: Children of the Plains,” a “20/20? special with Diane Sawyer. Watch a sneak peek of Diane Sawyer’s interview with Alaina below: