Sewickley Academy students Daniel Petricca and Alex Proie remember the moment when they learned they were going to perform a play with 18 of their classmates in Edinburgh, Scotland.

Daniel, 16, said he was "ecstatic" at the news, and Alex, 15, said she could only respond, "You're kidding!" when theater teacher Stacy A. Donovan called last year to say they were going to the Fringe Festival in Scotland in August.

They have reason to be thrilled, Ms. Donovan said. For a high school to be invited to attend the prestigious international theater festival is "a pretty darn huge thing," she said.

Called the largest performing arts event in the world, the three-week Fringe Festival attracts half a million visitors each year to more than 1,800 productions across Edinburgh.

Part of the Fringe Festival is the American High School Theater Festival, for which high school theater groups must be nominated by a theater professional or college faculty member and then go through a rigorous application process.

This is Sewickley Academy's first invitation to the Fringe Festival. Only 32 U.S. schools will perform there in August.

Ms. Donovan, who is in her second year of teaching theater at Sewickley Academy, said she didn't know who had nominated her students. But she said she knew the nomination was for their April 2007 production of "The Laramie Project," a groundbreaking piece that explores the murder of gay University of Wyoming student Matthew Shepard.

Daniel, who lives in Burgettstown, said the choice of "The Laramie Project" was characteristic of Ms. Donovan's approach to teaching theater. For Sewickley's production of Moliere's classic 17th-century farce "Tartuffe," students reframed the play as a comic performance by a down-and-out French theater company in the 1950s.

"We rewrote 'Tartuffe,' " he said. "That's no small feat."

The play ended its run to sold-out audiences this month.

Ms. Donovan has assigned about 50 of her older students the task of writing an original play for performance at the Fringe Festival.

Called "The Box," the production explores the nature of evil through an examination of the myth of Pandora's Box. It will feature movement, lights and sound also created by students.

Students are collaborating on the script now and will present "The Box" as their spring production, then rework it for its final appearance in Edinburgh.

For those students whose families can't afford the estimated $5,500 to $6,000 required for the trip, Sewickley Academy has guaranteed the funds to ensure all 20 can go.

Alex, who lives in Ohio Township, said she was looking forward to learning from the cutting-edge work on display at the Fringe Festival in both professional and high school productions.

Daniel said he was excited about presenting an original work to an international audience. "We're creating this thing from scratch," he said. "And it's a good feeling to think people are going to see it and know we made it."

Both students praised Ms. Donovan for her efforts to push them beyond their comfort level and encourage them to take advantage of opportunities such as the Fringe Festival and more.

At her encouragement, the two students, along with fellow Sewickley Academy student Walter Nogay, spent a month last year in a chateau in Brie, France, taking theater courses as a part of a new program called Acting Abroad.

"We're doing really innovative work," Alex said of her school's theater program. "It gives us an edge, and it shows what we can do, even at the high school level."

Ms. Donovan pointed out that she and her students still have a lot of work to do before going to Edinburgh.

But she expressed confidence that "The Box" will carry the school's developing tradition of theater innovation overseas: "I figure, the kind of work we do, we're perfect for this festival."