Four days after parents say they were told that a mold problem was under control at their Takoma Park school, there was a new outbreak: Small mold blotches were found in 11 classrooms, one hallway and three other rooms, according to school officials.

Parents at Rolling Terrace Elementary School have worried mold is sickening their children since a widespread outbreak in September. They have met with school officials, testified before county officials and called for a health survey.

On Nov. 4, PTA members say an outside contractor hired by the school system, Building Dynamics LLC, met with them and described the situation as stable and being remedied. No mold had been seen for a couple of weeks at the school of nearly 900 children. At the time, parents said they were glad for the progress, but would remain vigilant.

On Nov. 8, school system officials said the new mold appeared in small amounts on walls and some chairs in 15 areas.

“We’re just frustrated,” said Michaela Johnson, a PTA co-vice president, who said that many parents believe the mold’s source has never been discovered, which has led to recurrences.

“Here we are with very cold weather, heaters running, and we’re still getting mold,” she said. Johnson said her daughter has had asthma flare-ups she believes are related to recurring mold or to the chemicals being used to clean it.

“This constant exposure . . . is not acceptable,” she said.

School officials have maintained the building is safe. Dana Tofig, a spokesman for Montgomery schools, said the problem is continuing to be addressed and monitored.

An official with Building Dynamics said the school system would respond to media inquiries, not the company.

School officials have attributed the mold outbreak to a humid summer, improperly set thermostats and a malfunctioning mechanical system.