The city’s Educational Construction Fund is reviewing proposals for construction of high-rise apartment towers on the sites of two public schools near Lincoln Center — P.S. 191 on West 61st Street and P.S. 199 on West 70th Street, which was designed by the modernist architect Edward Durell Stone — and another school on East 96th Street, the School of Cooperative Technical Education. In each case, new schools would occupy the lower floors of the new buildings.

Officials have mingled private development and schools before; the new High School of Art and Design on East 56th Street is a prime exhibit. But the pace is accelerating. Three projects have been executed since 2008, and the latest proposal would sweep up three schools at once.

“We anticipate that we will be able to bring this successful model to other high-density zoning areas of the city,” said Erin Hughes, a spokeswoman for the Education Department, pointing to the success the department has had creating new classrooms on the Upper East Side.

Ms. Frey said she worried that “kicking students out of their home school is not a gentle process” and that “there will be an immediate negative impact on learning.” At a meeting last month, she said, an official of the Educational Construction Fund said that students from P.S. 191 would be moved to the Beacon High School building while the school was demolished and rebuilt, but that a relocation site for P.S. 199 had not yet been identified.

Meanwhile, the New York City Housing Authority, facing the biggest deficits in its history, has proposed letting developers build private, mostly market-rate residential towers on parking lots alongside eight housing projects in Manhattan. The authority would use the resulting lease payments — as much as $60 million a year — to pay for badly needed repairs in the 179,000 apartments it manages.

And this month, Mayor Michael R. Bloomberg announced that the city was selling off two municipal buildings near City Hall — 49-51 Chambers Street and 346 Broadway. City Hall officials boasted that these “well-positioned properties” would generate almost $250 million in revenue and savings and also lead to the creation of a public digital arts and media space inside one of the buildings.