About a hundred third-and fourth-graders, black, white and yellow, sit in a room in New York's P.S. 59, surrounding a drummer, a bassist and a white-haired Englishwoman at the piano. She is conducting a sort of kids' version of Name That Tune. Asking the children to listen carefully, she sends her authoritative fingers skimming over the keys, transforming a familiar ballad into eight-to-the-bar jazz. Cut. Do they recognize it in its new version? The kids chorus, "You Are the Sunshine of My Life." Right on.

For more than 15 years Marian McPartland (who with Mary Lou Williams is one of the reigning queens of the jazz piano) has been visiting grammar and high schools in the New York and Long Island area to introduce the sound of jazz to youngsters reared on little but rock.

Marian's educational avocation began when a Rochester, N.Y. deejay suggested she give local high school students a demonstration of the fundamentals of jazz. She was dismayed to learn that "a lot of them had never even heard of Duke Ellington, or Count Basie, or Coleman Hawkins. From that moment it became something of a crusade with me." Taking the initiative as she went from gig to gig, she spread the word among teachers that she was available to play for school groups. Her own training at Britain's Guildhall School of Music, plus her experience with jazz immortals Fats Waller, Art Tatum, Bud Powell, Teddy Wilson—and ex-husband, cornetist Jimmy McPartland—gave Marian, now 56, a vast jazz legacy. She has supplied the passion to pass it on.

The McPartland classroom technique is essentially pied piper. At first kids respond by keeping time with hands, heads or shoulders, then usually become so involved in the trio's music that they simply listen and watch, motionless. The jazz teacher's finale calls for the students to take tambourine, maracas and cymbals and improvise with her. For the old pianist and the new percussionists, it is a noisy and joyful moment.

Marian McPartland remains very much a performing artist. In Manhattan clubs like Michael's Pub and the Cafe Carlyle, where she's in residence for the month of January, the pianist can still fill a room. Whether dedicating Royal Garden Blues to "my dear friend Jimmy McPartland" or making Send in the Clowns a symphony of delicacy, McPartland transports her listeners to such vanished jazz temples as New York's Hickory House or Kansas City's Interlude.

When McPartland came to the States from England in 1946, she recalls that it was difficult for her to break into jazz because she was white, British and a woman. The music world of course accepts her now, but she wondered whether her race might be a problem in American classrooms because of jazz's black roots. Teaching last year in Washington, D.C. public schools—with a 96 percent black population—she encountered some minor problems with skeptical teachers, but found "all the children open and receptive." While in the capital she arranged for the late Duke Ellington to play for the schoolchildren. "I don't think the lives of the kids who heard him will ever be the same," she says. "And as the Duke changed their lives, so they changed mine."