Sage Ryan has never been a regular kid.

At age 7, he growled a blues tune with his grandpa on “America’s Got Talent.” At 11, he appeared in “Gianni Schicchi,” Woody Allen’s debut as an opera director. At 14, he enrolled at UC Berkeley — as a transferring junior.

Now Sage is a 17-year-old college graduate. And, true to form, he wants to be the youngest substitute teacher in the state.

But the San Francisco Unified School District, to which he applied, isn’t interested in sending the educational version of “Doogie Howser, M.D.” into classrooms. When officials found out his age, they rescinded a job offer.

“I put in all this time and it didn’t happen,” he said. “They never said anything.”

It was the perfect job, Sage figured, paying about $150 a day and offering needed flexibility as he pursues a career in film and television. He applied, passed the basic skills exam, submitted a clean tuberculosis test and went through a background check.

San Francisco Unified hired him, and he attended an orientation for new subs. That’s when school officials realized he was 17.

Sage likens his treatment to age discrimination, though in legal terms that typically applies to those on the other side of the spectrum — people over 40.

Technically, there’s no reason a 17-year-old can’t teach, as long as the individual fulfills all requirements, state officials said. But San Francisco district officials said they couldn’t hire someone like Sage.

“If someone is under 18, the school district can’t comply with its statutory duty to do a thorough criminal background check as the Department of Justice doesn’t release information about any crimes committed prior to the age of 18,” said spokeswoman Gentle Blythe. “We usually have several years of adult records to demonstrate that a person is mature and responsible — so far as criminal records show — to handle supervision of students.”

District officials declined to say how old applicants need to be to teach in city schools, or if Sage could be hired when he turns 18 in August.

Michelle Parker, president of the San Francisco Parent Political Action Committee, said a juvenile substitute teacher might not be well received by parents.

“Age doesn't always mean you have wisdom, so I’m thinking that,” she said. “At the same time, you can’t even vote.”

Parker also wondered how a teenager would fare given that “substitutes are the least respected of any adult that walks into a classroom.”

The irony, Sage said, is that the traditional school system didn’t work for him when he was a child, growing up in San Francisco, Los Angeles and other places. The typical classroom, he said, wasn’t flexible enough for his wandering mind.

The system is “unable to adapt to those who don’t fit the mold,” he said. “It’s frustrating.”

The boy tried to fit in, said his mother, Jessica Dirschel. Over 10 years, they tried 23 schools, including public, private, charter and even an arts-focused boarding school.

When all else failed, Sage’s mom homeschooled him, and at age 11, he started taking community college courses.

“He found it easier to focus on one topic at a time rather than jumping around in a normal school day,” said Dirschel, a third-grade teacher at San Francisco’s Rooftop Elementary and an alternative schooling consultant.

Sage earned his high school diploma at home, while simultaneously earning two years of college credit. At the same time, he did commercials, movies including “A Christmas Carol,” television and voice-over work.

When he was 14, he applied to a handful of universities. Woody Allen wrote a recommendation letter to USC, but he didn’t get in. After UC Berkeley accepted him as a transfer, he lived in off-campus cooperative housing with other students. He graduated in December with his peers, most of whom were at least 21.

Unlike many children who attend college early, Sage wasn’t an academic phenom, his mother said.

“The reason he went to Berkeley is not because he was a super smart kid,” she said. “It’s because the traditional school system failed him.”

Dirschel believes the system is failing him again. He’s out potential wages, and has spent months waiting for the district to process his application and send his paperwork to the state Commission on Teacher Credentialing.

While Sage could have worked for San Francisco — it was the sponsoring district of his substitute credential — he now he has to wait to get state certification to teach in any district, he said.

He’s decided to head south, where he lined up an interview with Los Angeles Unified, and will be pursuing work in Hollywood. He has agents in both San Francisco and Los Angeles.

“The ideal and conceivable thing for me is to be acting and writing and directing for sketch comedy,” he said, citing “Portlandia” as the kind of production he admires. “Comedy is my passion.”

But he still wants to be a substitute teacher. He had hoped to land in elementary classrooms, where he might encounter students struggling like he did and encourage them to believe in themselves.

He thinks his experiences — rather than his age — would help him relate to a lot of students.

“I've had a lot of rejection,” he said. “I’m going to keep trying to make it happen.”