The invitation Mayor Bloomberg extended yesterday to 25% of the city’s schools to join a bureaucracy-reduced “empowerment zone” where schools operate outside of the normal districts, immediately raised questions among some education experts about the future existence of the city’s school system.

Under the plan unveiled yesterday at a high school in the Bronx, 331 schools will join together to form the empowerment zone where principals can choose their own reading, math, and sex education curriculum. They will also control an additional $250,000 a school that can be used for teacher training, art programs, or the hiring of additional teachers.

“It’s an unprecedented move to in effect remove a quarter of the schools from the districts and to essentially remove them from the school system,” an education historian and research professor at New York University, Diane Ravitch said. “At the end of the day you will wonder what the school district will look like in five years, in 10 years. And will there be a school system?”

Earlier this year, the schools chancellor, Joel Klein, announced plans to add 150 schools to the 48 schools that are already operating in the program, which until recently was known as the “autonomy zone.” Instead, the education department has accepted 331 of the nearly 350 schools that applied to the program.

The shift to a decentralized system represents a reversal from four years ago, when Mr. Bloomberg took control of the city schools and centralized all decision-making – including how teachers should organize their bulletin boards – at the Department of Education’s headquarters at the Tweed Courthouse.

“It’s not about getting rid of the school system, its about structuring the system around schools,” a spokesman for the Department of Education, David Cantor, said.

Seizing on the four-year anniversary of mayoral control, Mr. Bloomberg yesterday joined the city’s schools chancellor at Fannie Lou Hamer Freedom High School in the Bronx to announce the expansion of the empowerment zone.

Mr. Bloomberg also announced that he would redirect $80 million in spending from the central and regional offices and cut about 350 jobs to fund the effort.

Another 140 jobs will be created to oversee the empowerment zone schools.

“Our public school system is not being run for the employees of the Department of Education. It exists and is being run for the students … and that’s the biggest difference maybe between today and before you had mayoral control,” Mr. Bloomberg said yesterday in the Bronx. “It’s just a whole different focus on what we’re trying to do. And sometimes that’s painful, sometimes it’s pleasurable, but whatever it is, we are going to do it.”

The plan puts the city’s principal’s union in awkward spot because the union represents both school principals – who could potentially benefit from expanded control over their schools – and education administrators, some of whom stand to lose their jobs.

“This rather vague proposal smells of apple pie and cinnamon, but leaves too many questions unanswered,” the president of the Council of School Supervisors and Administrators, Jill Levy, said yesterday.

“At first glance, the promise of empowerment of principals appears to be real. Yet, those of us who understand the nature of schools and the principal’s role see that many of the ‘new empowerments’ are simply functions that principals perform already. If the performance agreement is read carefully, the empowerment becomes illusory. The document is laced with statements concluding that principals are empowered unless and until their CEO says they are not,” Ms. Levy said.

The union filed a complaint with the state Public Employment Relations Board last month over the empowerment zone, charging the Department of Education with unfair labor practices.

Other education experts raised concerns yesterday about whether the increasing number of young principals with few years of experience would be ready to handle the added responsibilities.

A senior fellow with the Manhattan Institute, Sol Stern, accused the department of “just rearranging deck chairs on the Titanic.” He said that the administration keeps changing its mind about how it wants to improve the system.

When Mr. Bloomberg took control of the city’s schools, he created a more top-down system by replacing the city’s 32 community school districts with 10 instructional regions.

Under a court settlement, the Bloomberg administration agreed to keep some offices in the 32 school districts in order to comply with state law. A plaintiff in that lawsuit, Senator Kruger of Brooklyn, and Ms. Levy said yesterday that they planned to challenge the expansion of the empowerment zone in court because it removed almost one-quarter of the city’s schools from the district and regional structure.

Mr. Klein said yesterday that the department had transformed a “messy” and “bureaucratic system.”

“These schools are critical to moving our entire system forward,” Mr. Klein said. “The more than 300 principals who are ready to take on the dual challenge of responsibility and accountability have made a powerful statement. They want to be leaders who are prepared to set ambitious goals, make more decisions about their schools’ destinies, and constantly push to make progress.”