Bloomberg's administration has closed a total of 164 schools and replaced them with 654 new ones. In total, roughly 1,100 schools are co-located inside 538 buildings; Charters make up 10 percent of them.

Sharing buildings has required some schools to give up classroom space, and to coordinate gym and lunch times. There has been friction in some communities between the charter and regular district schools.

The old Stevenson high school building in the Bronx is now home to nine different schools, with 3,500 children from pre-K through high school, the most in the school system. D.O.E. officials told council members that the average co-located building housed 2.5 schools.

The Department of Education is required by state law to notify communities in advance of any changes to a public school building and to hold hearings. In practice, council members said, there is little public input because the Panel for Educational policy, charged with approving any new schools or co-locations, is controlled by the mayor and has never voted down a proposal.

Council members have proposed three non-binding resolutions to curb the city's power to force schools to share space. One would require local Community Education Councils to approve any co-location before it could advance to the Panel for Educational Policy, effectively giving these councils veto power. Another would set a one-year moratorium on co-locations beginning next July. The third would require more community notification of any changes in the use of the school building.

The teachers union has proposed adding requirements for charter schools seeking free space in public school buildings. It wants them to publicly disclose financial data and all political donations, along with their student demographics, suspension rates and attrition rates for teachers and students.

How can we make everyone do it this way?' but 'How can we best serve everybody?'"