Ensemble ACJW Riffs on Stravinsky at Weill Hall To its sponsors, the Ensemble ACJW's mission is primarily educational. The players in this two-year fellowship program - a joint project of Carnegie Hall, Juilliard, the Weill Music Institute and the New York City Department of Education - teach in schools in all five boroughs and perform in community programs around the city. But to those of us who know ACJW only through its concerts, the ensemble has become a valuable part of New York's musical fabric. That is especially true when it presents thoughtful, invigorating programs like the one at Weill Recital Hall on Tuesday. The heart of the program was a finely turned account of Stravinsky's "Soldier's Tale" ("Histoire du Soldat"). But instead of filling out the evening with unrelated scores (by Stravinsky or otherwise), the group and Carnegie Hall commissioned members of the Sleeping Giant composers" collective to write a companion piece, "Histories." Sleeping Giant includes six Brooklyn composers, four of whom - Andrew Norman, Christopher Cerrone, Jacob Cooper and Robert Honstein - contributed to "Histories." The other two are Ted Hearne and Timothy Andres. Using the same septet instrumental scoring as Stravinsky, the four composers cast their movements as responses to this chamber piece, occasionally quoting from it directly, or at least alluding to it. In some ways these are remixes, in current musical parlance. They take elements of the original - a percussion flourish here, a violin or trumpet phrase there - embroider them ambitiously with new material and build new structures around them. The set has its own overall architecture as well, thanks largely to Mr. Norman's four aphoristic contributions - "In," "Between," "Through" and "Out" - which begin and end "Histories" and connect the other movements. These are wild, cacophonous pieces, but from within each a single, lyrical line shines through the welter of sound. In "Agitated, Stumbling Like an Endless Run-On Sentence," Mr. Cooper used the percussion writing toward the end of "The Soldier's Tale" as the starting point for a robust fantasy, at times transferring the high-energy bursts in Stravinsky's music to the brasses and woodwinds and strings. Mr. Cerrone sent the woodwinds and brasses up the aisles, where they mostly produced toneless, breathy sounds to accompany the vibraphone and strings in "Recovering," an eerie magnification of a fragment from the only moment of repose in the Stravinsky, the "Pastorale." And Mr. Honstein built a few Stravinskian gestures into "Marionette," an abstract assortment of explosive figures in constantly changing combinations of timbre. The spirit and focus that the ensemble brought to these pieces also informed its approach to "The Soldier's Tale," though the familiarity of the Stravinsky allowed them a flexibility that was not yet apparent in the new pieces. Stravinsky's acidic harmonies and sassy rhythms came through vividly, and Keats Dieffenbach brought the right touch of rustic brashness to the prominent solo violin line. The actor Gabriel Ebert, a superb narrator, used accents, gestures, vocal timbre and a couple of hats to create the characters in this contest between a soldier and the devil.