Beyonce did a bit of good in the hood yesterday (May 3, 2011) when she surprised a group of students at Harlem’s PS/MS 161.

As you know, Bey is apart of First Lady Michelle Obama’s “Let’s Move” initiative to fight childhood obesity, and she created a dance routine to encourage students to get up and move.

[WATCH: Beyonce’s OFFICIAL ‘Let’s Move’ Video]

The Harlem middle school students were were participating in the four-minute flash dance routine simultaneously with other middle school students and at 1:42 pm EST others around the country began to dance.

Can you imagine how shocked the students were when THE Beyonce appeared out of nowhere and began to dance along with them? Hilarious!

… and while Bey was holding it down in Harlem, the first lady was gettin’ her “dougie” on in DC!

Watch both videos PLUS more photos below:

Video: Beyonce Surprises Harlem Students During “Move Your Body” Routine

VIDEO: Michelle Obama Talks to DC Students about LETS MOVE

VIDEO: Michelle Obama Does “Lets Move” in DC