VIDEO: See How Sierra Boggess Warms Up For a Performance of SCHOOL OF ROCK

She may play the uptight Principal Mullins in SCHOOL OF ROCK - THE MUSICAL, now in previews at Broadway's Winter Garden Theatre, but before performances she looks cool as a cuke, clowning for the camera with a very special warm-up routine.

Based on the smash hit 2003 film of the same title, School of Rock - THE MUSICAL will feature music from the movie, as well as an original score by Andrew Lloyd Webber and lyricist Glenn Slater, with a book by Julian Fellowes and direction by Laurence Connor (currently represented on Broadway by Les Miserables).

SCHOOL OF ROCK - THE MUSICAL follows Dewey Finn, a failed wannabe rock star who decides to earn a few extra bucks by posing as a substitute teacher at a prestigious prep school. Completely disinterested in academic work, Dewey decides to create his own curriculum, turning his class into a guitar-shredding, bass-slapping, mind-blowing rock band.

Warner Bros. Records will release the Original Broadway Cast Recording for SCHOOL OF ROCK - THE MUSICAL on Friday, December 4, 2015, on the eve of opening night. The new album will feature a new score by Andrew Lloyd Webber and lyricist Glenn Slater, along with three songs from the immensely popular 2003 film. Three-time Grammy Award-winner Rob Cavallo, who has worked with Green Day, My Chemical Romance, Paramore, Goo Goo Dolls, Phil Collins, and Gary Clark Jr., produced the album along with Lloyd Webber.