charter school

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A public school operated independently of the local school board, often with a curriculum and educational philosophy different from the other schools in the system.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun US A particular alternative to public school. Usually more focused on students studying on their own at home and infrequently checking in with the school.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an experimental public school for kindergarten through grade 12; created and organized by teachers and parents and community leaders; operates independently of other schools