Matthew Perry, formerly of the hit show 'Friends', stars in 'The Ron Clark Story' Sunday on TNT at 7 p.m.

Matthew Perry may have been a troublemaker back in high school, but he earns high marks as an inspirational teacher in The Ron Clark Story, a fact-based TNT original movie premiering tomorrow night at 7.

Best known as wisecracking and cynical Chandler Bing in NBC's long-running sitcom Friends, Perry really puts his heart into his portrayal of Clark, the idealistic young North Carolina teacher who moved to New York to work with at-risk teenagers in an inner-city high school, transforming the lives of his students with his combination of positive reinforcement backed by strict discipline.

"It presented an interesting challenge," Perry says of his role. "Before we started, I had decided not to try to do an impersonation of the guy. I wanted to capture the spirit and essence of Ron, so I read his book, and we corresponded with each other on email.

"What I liked about the guy, and what came across in the script, is that there is no real sense of irony about him. He was just one of the nicest people in the world, which I worried might not come across as interesting. Fortunately, Randa Haines, the wonderful film director, had my back and assured me that it was still interesting. I had to drop my own cynical nature, which was easier once I met the kids."

Clark, whose personal story caught the attention of a producer when he appeared on Oprah Winfrey's TV show after being winning Disney's prestigious Teacher of the Year Award in 2000, says he was happy but a little surprised when he heard Perry had signed to portray him.

"I thought it was great, because I had watched him for so many years on 'Friends' and knew how people have such a strong connection with him," Clark says from his current home in Atlanta, where the Ron Clark Academy is nearing completion.

"When I met him, I asked him why he agreed to do it, and he said, 'Well, when I read this script, there was substance to it and it made me cry. I knew if it touched me, it would touch other people'."

Clark, who was first approached about this project six years ago, says he had become a little sceptical that it ever was going to happen, but he was impressed by the attention to detail that the filmmakers invested in telling his story.

"When they started filming, they were calling me every day asking for more details: 'Ron, we're decorating your apartment in Harlem. What did your have on the refrigerator, magnets or pictures? What kind of pictures were on your nightstand'?" Clark says. "I sent them a photograph I had had of me with my family, and they actually got actors to pose with Matthew Perry in the exact same positions as we were in that picture. It was very strange to see when I walked on to the set later."

Occasionally, however, reality took a back seat to Hollywood, Clark concedes.

"At one point in the movie, they had Matthew holding a jar and having the kids spit their gum into it as they come out of the classroom," he says. "I never would have done that. Also, there's a student named Julio in the movie who sits on his desk - on it, not in the seat. Matthew lets him get away with that, but I never would have.

"I was much more strict than Matthew is in the movie. At one time (in the movie) a student says, 'No, fool!' to the Mr. Clark character and he lets it go, but I never would have let her get away with that. I would have been ranting and raving!"

Playing the inspirational Clark gave Perry a chance to acknowledge another teacher who had made a difference in the actor's life at a time when, he admits, he was less than a stellar student himself.

"I was actually kind of the class clown," Perry says. "Any oppportunity to distract from learning, I would make a joke and get myself into trouble. I was sort of a handful. In fact, in the sixth grade, my desk was placed in the back of the room, facing the wall.

"A teacher in Ottawa named Greg Simpson noticed my antics and directed them into theatre, which was very smart of him. He was my math teacher, but he was also the theatre teacher, so he noticed me during math class - which was a very tough class for me - and used my antics to the advantage of plays and, hopefully, my acting career later on. I've always been very, very grateful to him for doing that."