Usually students do the experimenting at school, but it is the failing Philadelphia school district that will be the focus of a far-reaching educational experiment. With an agreement reached Friday, it will become the largest system ever to be taken over by a state government.

Gov. Mark Schweiker and Mayor John F. Street have opened the door for a private school management company to take control of dozens of the district's decrepit schools. For-profit Edison Schools Inc., will most likely help run the 210,000-student district.

"We want to assure the students of this city we have your best interests at heart," Street said.

The plan was announced after weeks of negotiations on the future of the country's seventh-largest school system. The state takeover went into effect at 12:01 a.m.

The Philadelphia Federation of Teachers said it would challenge the arrangement.

"We will fight any attempt to replace union-wage jobs with minimum-wage jobs," said Ted Kirsch, president of the union. "We will be relentless in our criticism if this deal turns out to be ... a political power grab that leaves kids out of the equation."

A $216 million budget deficit, low test scores, chronic teacher shortages and crumbling buildings are all reasons Schweiker has cited in calling for drastic measures to repair the district.

The school board will be replaced by a five-member commission, with three members appointed by the governor and two by the mayor.

The commission will hire a chief executive officer, decide how many schools will be privatized and negotiate contracts with private education companies. Businessman James E. Nevels, who has worked with private management of public schools, was appointed interim chairman.

Schweiker promised the district "a mountain" of new textbooks — one million — along with more teacher training and $75 million in new state money each year. Street promised an additional $45 million in city funding, while vowing there would be no new taxes.

"We have a full partnership," Schweiker said. "And to that end, I believe we will give rise to the finest urban school system in the United States."

Last summer, former Gov. Tom Ridge contracted with Edison to conduct a $2.7 million, two-month study of classroom and financial management within the Philadelphia district.

State officials have since been negotiating with Edison on a contract believed to be worth more than $100 million. Under Schweiker's latest plan, Edison would be hired to advise the central management of the district and run as many as 45 schools.

The reform commission will have the final say, but Nevels called Edison a "great company." Nevels was part of a similar state-appointed commission in the suburban Chester-Upland School District, where Edison runs nine of the 10 schools.

Across the nation, 18 states have seized control of 40 districts, and some places — including Baltimore, Minneapolis and Hartford, Conn. — have tried private management of individual schools.

Schweiker's plans for the Philadelphia school district has generated fierce opposition from teachers, minority leaders, the school board, City Council, and parent and community groups.

Public-school advocates say what the district really needs is more money for smaller classes, early childhood education, new textbooks and upgraded buildings — not a state takeover or a private company.

About two dozen protesters occupied the school administration building Friday, camping out in the vacant office of Phil Goldsmith, who resigned as interim chief executive officer last week after condemning the state takeover as a "charade."

A small group of protesters also filled an intersection outside the Pennsylvania Convention Center, where Street and Schweiker announced the agreement.

"We will be satisfied when there is no option of privatization on the table," said Katie Sipp of the advocacy group Jobs with Justice.

The Associated Press contributed to this report.