What's a Co-op?
A parent cooperative preschool is organized by a group of families with similar philosophies who hire a trained teacher to provide their children with a quality preschool experience. The preschool is administered and maintained by the parents. The parents assist the professional teachers in the classroom on a rotating basis and participate in the educational program of all the children. Each family shares in the business operation of the school (usually a nonprofit venture), thus making it truly a cooperative venture. Parents, preschool children and their teachers all go to school together and learn together.
Excerpt from Parent Cooperative Preschools International