Washington area school systems opened the year with more than 7,000 newly hired teachers after an intensive recruiting season shadowed by an approaching federal mandate to have a highly qualified teacher in every core academic class.

In several systems in Virginia, Maryland and the District, school officials said they hired more teachers than the year before. Many are still hiring.

Montgomery and Prince George's counties have about 100 vacancies each, and the District's public schools had nearly 70 as of last week. Fairfax County also was hunting for teachers even as its schools opened Tuesday.

Whether school systems will be able to meet the new federal teacher quality requirement by next summer's deadline is unclear. With some exceptions, the law calls for teachers to hold a bachelor's degree and a full state teaching credential and demonstrate competence in the subjects they teach.

School administrators said they are pushing hard to meet the requirement. But teacher quality rules vary widely from state to state, complicating efforts to gauge the impact of the federal requirement, which is a provision of the No Child Left Behind law that President Bush signed in January 2002.

Virginia officials estimated that 94.5 percent of public school classes that handle core academic subjects -- such as English, reading, mathematics, foreign languages, history and science -- were staffed by highly qualified teachers in 2003-04, the latest year state data were available. That was up from the previous year's figure of 83.5 percent.

At Stenwood Elementary School in Vienna, which has two new classroom teachers, Principal Laraine Edwards said she hires only candidates who meet the highly qualified standard. "I never want to settle," she said.

Virginia data support her assertion: All of Stenwood's core academic classes had a highly qualified teacher as of 2003-04.

In Maryland, by contrast, the percentage of core academic classes with highly qualified teachers was 75.3 percent in the 2004-05 school year and 66.9 percent the year before.

On their face, those figures seem to show that Maryland has fewer high-quality teachers than Virginia. But some experts said Maryland simply has tougher rules. A December 2004 report from the National Council on Teacher Quality, based in Washington, analyzed how states designate veteran teachers as highly qualified. It gave Virginia's rules a D, saying they had "little rigor," and Maryland's a B-plus, calling them "tough."

The federal law gives states significant leeway to define what veteran teachers must do to show subject-matter expertise. In some cases, teachers can get credit for professional development or school activities that have little or nothing to do with content mastery. Critics call that a major loophole.

Virginia Education Department spokesman Charles Pyle said the state's teaching force has demonstrated its caliber in recent years. He cited rising SAT scores for college-bound students and state test scores that are helping Virginia move toward student achievement targets under No Child Left Behind. "Our teachers are producing results," Pyle said.

The teacher quality report did not grade the District's rules. Tony Demasi, human resources executive director for the D.C. public schools, said no data were available on how many classes lack highly qualified teachers. U.S. Department of Education spokesman Chad Colby said yesterday that the federal government is seeking the data from the District.

Complying with rules is one matter; staffing classes on opening day is another. Area school systems hired more than 7,000 teachers for the new school year in response to shifting development patterns, perennial teacher turnover and academic initiatives.

In the District, Demasi said he hired 497 new teachers for opening day, for a staff of about 5,200 teachers. In previous years, he had hired about 400. He said the school system began hiring sooner than usual this year -- a move that paid off with a smooth opening day. In previous years, human resources staff were working round-the-clock to fill vacancies after school opened. "Scrambling isn't the word for it," Demasi said. "I had people sleeping here overnight. We have come a long way."

Fairfax County hired more than 1,600 new teachers this year, for a total teaching staff of about 14,000, said Kevin North, assistant superintendent for human resources. That's 200 more new hires than the year before. "It's always very intense and very challenging to get the right number of the right kind of people in those slots at the beginning of the year," North said. He called the new federal requirement "a huge challenge" but said the system has been "working very hard on this for years."

Elsewhere in Virginia, Prince William County hired 781 new teachers, Loudoun County 737 and the city of Falls Church 29.

In Maryland, Montgomery schools hired 1,057 teachers, for a teaching staff of 11,279, said system spokesman Brian K. Edwards. That was up from 802 new hires the year before. In Anne Arundel County, there were 743 new teachers, and in Howard County, 473.

Prince George's hired 1,150 new teachers, for a staff of about 9,500, said interim schools chief Howard A. Burnett. He said about 16 percent of the new hires were issued provisional credentials, meaning in all likelihood they had not yet met the highly qualified standard. Burnett said the school system also was recruiting teachers displaced in the Katrina disaster. "We'd give those individuals an opportunity to be employed immediately," he said.

Teacher Tim Hudenberg gets a laugh out of Danielle Bennett, center, and other students at Westfield High School in Chantilly. The most recent figures say 94.5 percent of teachers in core classes in Virginia are highly qualified.