Commonwealth Shakespeare Company will receive a $100,000 matching grant from the National Endowment for the Arts, which the company — best-known for its free Shakespeare on the Common series — will use to fund a program called “Shakespeare OFF the Common.’’ “It’s a really big deal,’’ company artistic director Steven Maler said Wednesday. “The imprimatur of the NEA is such an extraordinary game-changer for CSC.’’ The “Shakespeare OFF the Common’’ project, devised in collaboration with the Mayor’s Office of Arts, Tourism and Special Events, will unfold in three stages, and will revolve around a new troupe of young theater artists called “CSC II.’’ First, Boston public school students will be introduced to “Romeo and Juliet’’ by means of workshops and curricula. Then will come a production of “Romeo and Juliet’’ by CSC II at the Strand Theatre in Dorchester that will be open to Boston students and local residents. And then CSC II will trim down Shakespeare’s tragic love story to a one-hour version for a “Tour of the Parks’’ in 2015, during which the play will be performed in neighborhood parks, using the sets and costumes from the full-length production. Performances will also take place at several venues near Boston Boys and Girls Clubs.