Children from the Jackson Mann K-8 Community Center (JMCC) in Allston performed a flash mob in locations throughout the city on Monday, including on Guest Street in Brighton.  JMCC's Rosie Hanlon explained that the performance was the culmination of the center's summer program, which included instruction in dance, music, art and creative writing. Each year, JMCC creates a theme for their summer program, and this year's theme was "Peace and Harmony."  Hanlon said that the theme was chosen in an effort to help combat bullying.