Montgomery County public schools will resemble ghost towns today, as students begin a long weekend and teachers take a scheduled day off without pay.

The students will also be missing from Howard County schools, though many teachers will be at their desks working on lesson plans and will get paid for the day. The same goes for most of Maryland's 24 school districts.

But then there's Allegany County, where classes will be held as usual. The Western Maryland district is alone in defying a tradition of closing public schools for the annual convention of the Maryland State Teachers Association, which began last night and ends Saturday night.

"It's going to be the same, regular Friday [class] schedule," said Debbie Pappas, the vice president of the Allegany County teachers union, who resigned from the district's calendar committee in protest of that decision. "We were given so little credibility as far as our input."

The day off from school has long been sacred to state teachers union officials -- if not for a majority of teachers.

About 3,000 of Maryland's 60,000 union members are expected to attend this week's convention in Ocean City, said a union spokeswoman, who added that other teachers will attend separate professional conferences or take part in staff development in their counties and cities.

In Virginia, by contrast, schools do not close during the state's annual teachers convention, which is usually held in April and sometimes coincides with spring break.

The battle in Allegany between union leaders and district officials highlights a struggle that other Maryland school systems face, balancing the interests of teachers who say they are overworked with concerns of parents who don't want their children deprived of instructional time.

Enordo Arnone, an Allegany school board member and former teacher, said the board agreed to find substitutes for teachers who wanted to attend the convention. But when he looked at a calendar and realized how often the county's schools would be closed next month because of the Nov. 2 elections and Thanksgiving, he could not justify giving teachers another day off.

"Sometimes you don't have a choice," Arnone said, "because you have a lot of testing with the children that the state requires."

The federal No Child Left Behind Act has introduced rigid standards for teachers as well as students, including penalties for failing to succeed on standardized reading and math tests. Some schools are rearranging their schedules to devote more time to core subjects and slicing minutes out of recess, leaving teachers searching for time to plan lessons or meet with students and colleagues.

As a result, teachers say they need more time and training at workshops and conventions to be able to meet the new federal goals.

"We view ourselves as a learning organization," said Lissa Brown, spokeswoman for the state teachers association. "We have always supported the idea that learning is never finished, and that means for people who educate people, too."

Brown said that because the teachers convention lasts three days, it overlaps with the school week. The conference has been scaled back at least once before; more than a decade ago, she said, most school systems shut down for two days to accommodate the schedule. Brown said the association was hesitant to hold events on Sunday because of religious conflicts and the need for travel time back home.

Bonnie Cullison, president of the Montgomery County teachers union, said the convention is held in the fall -- rather than during the summer when students are out of school -- to prepare to be politically active in local and national elections and legislative sessions.

Maryland's school districts vary in the ways they provide the time off for teachers. Most teachers in the D.C. suburbs will be paid for today, though students will not be in class. That means that if they do not attend the convention or another professional conference, they must report for work. In St. Mary's County, for example, coaches are slated for CPR training, said Jan Emerson, president of the teachers union.

In Prince George's County, however, union President Carol Kilby said teachers receive a full day of pay, but those who do not attend a professional workshop are on the honor system. "We're trusting their professional judgment to use their time wisely," Kilby said. "We have respect and trust for teachers to do the right thing."

In Montgomery, teachers will not be paid for today. Cullison said at least 100 teachers planned to attend the convention.

Though some parents say they recognize the need for professional development, they express frustration over the number of half and full days off during the school year.

"I have had parents say to me that it is a hardship to them a lot of times," said April Keyes, corresponding secretary for the Montgomery PTA.

Still, Keyes said that when she drives home from work at night, she often sees teachers' cars parked at her daughter's middle school in Germantown long after classes have ended.