NEW YORK (CBSNewYork/AP) – Students at a Harlem public school working out to a Beyonce song got a big surprise when the superstar walked in and joined them.

Click Here For More Information On Let’s Move

About 85 students at P.S. 161 were in the middle of a choreographed routine Tuesday to a song adapted from Beyonce’s hit “Get Me Bodied” when the singer joined in.

Beyonce who was wearing her signature stiletto heels, white skinny jeans and a ”Let’s Move” tank-top  jumped in line without even missing a beat.

The children were participating in a national simulcast of “Let’s Move Flash Workout” — a special event that was part of first lady Michelle Obama’s fitness campaign.

Beyonce rewrote and re-recorded her hit song for the event and called it “Move Your Body.” She also choreographed th routine for middle school students across the country and sent out instructional videos.

Thirteen-year-old Aisha Collier gushed “she’s so beautiful.” She told the New York Post she messed up a little when Beyonce first arrived but then got back into it and continued to dance and have fun.

(TM and Copyright 2011 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2011 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)