With class sizes swelling to as many as 40 students in some Baltimore schools this year, officials say they will transfer teachers between schools to keep class sizes manageable.
Crowding is apparently most acute in middle and high schools where large numbers of students were held back after the school board put stricter promotion standards in place last year.
Several other factors are contributing to the larger class sizes, including the creation of new high schools and the addition of a sixth grade to some elementary schools, both of which require student transfers.
The problem is not increasing enrollment - that has shrunk citywide by more than 10,000 students in the past five years, and stands at about 93,000.
Moving teachers from one school to another to ease crowding has not commonly been done in the beginning of a school year, and is likely to be a point of contention among teachers and parents.
Most changes are expected to take place the first week of next month. By then, children and their teachers will have spent about a month together.
"I think we should try to work this out and not try to cause any more havoc for teachers who have settled into the routine," said Marietta English, president of the Baltimore Teachers Union.
Some classes at Highlandtown Middle School and Thurgood Marshall Middle School are particularly large, said English, who visited certain middle schools after teachers complained.
How many teachers will be moved won't be known until next week, said Cassandra W. Jones, chief academic officer.
The school system has avoided such problems in the past, in part because it set aside a pool of money that principals could dip into at the beginning of September when they saw class sizes rising in a grade level.
But that money is not available this year, Jones said, because the system has allocated it for a general class-size reduction - to ensure there is one teacher for every 18 children in elementary school, one to 27 in middle school and one to 28 in high school. That means that the only way the school system can even out class size is to redistribute teachers.
Jones acknowledged that the plan to shift teachers is fraught with pitfalls.
If an English class at one high school has 40 students and a Spanish class at another has 20 students, Jones can't simply transfer the Spanish teacher to help out.
"I have to do the match by content," she said.
And teachers who are certified to teach in middle school cannot be moved to the high school level unless they are certified to teach high school students, as well.
Jones said principals will work together to see first which staff can be moved around within a school to solve the problems.
"We need to let the principals address this because we don't want to disrupt the school day," Jones said.
The teachers union is concerned about transfers.
"We would hope that we could work with the system to work out a fair and equitable transfer policy," English said. "I would oppose the wholesale removal of a teacher from a high school to a middle school."
The most disruption would be caused if elementary school teachers were moved because young children often develop close relationships with their teachers, she said.