The orchestra is a remarkable chameleon. At Saturday's second family concert of the season, the Philadelphia Orchestra kept changing form - inhabiting a pure classical realm one moment, pops the next.

Conspicuously, the two coexisted in a single piece. Bill Holcombe's 'Twas the Night Before Christmas, conducted by Cristian Măcelaru and narrated by Charlotte Blake Alston (pictured), is a suavely packaged catalog of tunes, from traditional Christmas to Wagner's Siegfried horn call. Sometimes all it takes is a flash of a melody, a micro reference, to illustrate a portion of Clement C. Moore's poem. The piece, brought to the orchestra by its artistic administrator, Jeremy Rothman, was supremely satisfying - but mostly because the orchestra could sway so convincingly between its quick-silver changing idioms.

Young dancers from Pennsylvania Ballet II stepped onto the stage for excerpts from The Nutcracker. Sarah Lee, 19, as Coffee in the "Arabian Dance" was its chief pleasure, assured and poised.

Santa came down the aisle in Leroy Anderson's Sleigh Ride - music so happy you're sure its score is notated in smiley faces - and bounded up to the podium to lead the ensemble. As was the case in the Holcombe and Tchaikovsky, there's something enormously satisfying in hearing this music rendered in Philadelphia's generous, buttery sound.

The variety of the hour-long concert was great enough to make you believe you were hearing a pops concert. Paired with the integrity of the ensemble, there could have been no greater gift to Philadelphia tots.