It's an unusual film that has a public-school music teacher as the heavy, but "Music of the Heart," the new Meryl Streep vehicle, is that kind of movie. Based on a true story (and a 1996 documentary called "Small Wonders"), this is the story of Roberta Guaspari, a Navy wife and mother of two boys, who's devastated when her husband leaves her and must find some way to survive, financially and psychologically.

She's a prickly sort, short-tempered when the boys don't practice their violins, dangerously close to being a control freak. She was a violin teacher at a school in Greece when the family was stationed there, and now has a huge bin full of child-size violins. So one day she takes herself to Harlem, to an alternative public elementary school, whose principal (Angela Bassett) gives her a chance as a volunteer to teach violin to the children. Here's where the heavy comes in -- a tenured music teacher who tries to undercut her at every turn -- though we know he's just a little bump in the road.

Are there surprises here? Of course not. Roberta gets hired as a substitute, she teaches for ten years to increasing support by parents and kids, and the years are marked by every variety of slum event, from the death of a child in a drive-by shooting to disdain for a 'white' instrument, to the consequences of abusive parents. But the program grows, until the expected crisis, when the program is defunded by the district and Streep must put together a benefit concert for help.

What I like in the film is Streep's genius at conveying the essence of a not-very-extraordinary woman in a not-very-extraordinary life, without trying to sell us on her. She inhabits Roberta Guaspari, I'm certain, just as fully as the real Guaspari does, and if you think that's easy you're quite mistaken. Try it yourself, as an actor. Try finding and communicating the heart of an ordinary person in a way that makes her worth our time, even our love. Streep, already honored many times for her work, here shows her greatness by simply living inside the skin of an (almost) everyday being.

Of course Guaspari is not an everyday being. She's a committed, driving woman whose focus happens to be on teaching children to play the violin. Which she does. And the children respond to her in ways that make you cry. Slowly they improve, slowly they find the way to discipline themselves so they can practice at home in traumatic situations. Slowly the light of love for what they're doing begins to shine in their eyes. The film is wonderfully shameless in tugging at our emotions, and I for one was happy to let it all out.

Naturally, the film ends with a performance by the children at Carnegie Hall, and had it been as simple as that I would have wound up dehydrated from loss of fluid tears. But director Wes Craven, or writer Pamela Gray (she wrote the beautiful script for last spring's "A Walk on the Moon"), or perhaps the studio, undercut everything that came before when they gave the final ten minutes of the movie over not to the children but to the famous names who join them on stage, from Mark O'Connor to Itzhak Perlman to Isaac Stern. And so we see an all-star performance of a movement of Bach's Concerto for 2 Violins, as played by the all-stars, with only two of Guaspari's children joining them. The point of the concert, and of the film itself, is not that these children are geniuses or prodigies, but that they play the fiddle and love it. We in the audience don't need to see them give up their place in the limelight to professional concert artists.

Craven, known up to now only for his horror films, handles things here with skill and a good sense of staging and choreography. The children, though, are magnificent. Each one is different without being a cliché, and all are natural and spontaneous, a tribute to them and to the casting and direction.