Now here's a graduation story for the ages. This week, Jordan Thomas will trade his ID card at the Philadelphia High School for Creative and Performing Arts for a sweatshirt from the renowned Peabody Institute.

But the 18-year-old harp virtuoso is also a teacher. And the student he'll leave behind? Audrey Johnson Thorton, age 83.

Thomas has studied harp for nine years and taught Thorton weekly for 12 months. Role reversal is rarely as sweet as when a young man shows an old woman the magic of music.

Thomas is used to performing, but I had to persuade Thorton to let me watch one of their last lessons at her grand Alden Park apartment in East Falls.

As the the high school senior tunes Thornton's lever harp - with 27 strings, it takes 15 minutes - his octogenerian pupil offers a classic confession.

"I'm not practicing as much as I should," she says bashfully.

If Thomas is upset, he's far too respectful to show it. His own grandmother, who drove him to the lesson, is sitting off to the side watching, after all.

Thorton met Thomas at their church, St. Luke's, in Germantown. "He was just a boy with this wonderful gift."

Like Thomas, she had studied piano as a child. But it took Thorton, a wife and mother of three who ran a mental-health center and a summer camp, decades to fulfill her dream of learning the harp.

"At my age," she figures, "I should do what I want."

Tackling a classic

They begin with "Twinkle, Twinkle, Little Star," a child's song that is not as easy as it would seem on a complicated instrument like the harp.

Thorton sits erect, straining ever so slightly to read the notes from a book on the music stand. But her arms aren't in sync.

"Let's work," Thomas says gently, "on getting the right sound out of this instrument."

He adjusts her elbows and shows her how to angle her thumb.

Thorton tries again. She botches the melody, but even the missed notes are richer and longer-lasting.

"You're almost there," he says encouragingly. "Make sure all the fingers go toward the palm when you release them from the string."

This time, Thomas has her slow down the song so that "Twinkle, Twinkle" sounds like a dirge.

She plucks a few bars and hears an immediate difference. But that star could still be brighter.

"It's your nails," Thomas points out. "You should cut them."

Thorton's manicures are a comic sore spot. Thorton laughs. And as he does almost every week, Thomas drops the subject.

Learning by teaching

Thomas' own teacher, Elizabeth Hainen, didn't know much about his moonlighting until my call. She is pleasantly surprised.

"The best way to learn is to teach," says Hainen, principal harpist with the Philadelphia Orchestra. "It really helps you completely understand what you're doing if you have to put it into words."

Hainen marvels at Thomas' natural talent and drive.

"He has a presence, something special," she tells me. "He's shown complete discipline. He really learned to listen and use his ears."

The student-turned-teacher can be strict, Thorton admits, but he happily indulges her when she asks for a break so he can play.

"Watching him," she explains, "is a good learning tool."

Thomas begins a minuet. The space is transformed, as if a Jane Austen dance scene has jumped off the pages into a Philadelphia living room.

A delighted Thorton plays air harp right along, the closest she may get to mastering such a piece.

"There's joy you get passing the music to another person," Thomas acknowledges when I press him on what he has taken from the lessons. "Joy and fear."

Thorton feels similar emotions as she contemplates continuing her studies with someone else.

"I want to keep playing," she insists. "Jordan is going to be famous. And I was his first student."