Last night's scheduled homecoming dance at Rancocas Valley Regional High School in Mount Holly was postponed after the H1N1 death of a student last weekend and recent high absenteeism.

In Pemberton Township, 15 percent of the district's 5,000 students were out Wednesday, double the usual rate this time of year.

And in the Pennsylvania suburbs, attendance has been off 10 to 12 percent in past weeks, up to three times the norm. Some schools have reported as many as 23 percent of students absent; two parochial schools closed temporarily.

Whether it's H1N1, seasonal flu, a cold, or extra parental caution, teachers across the region are facing many vacant desks. And that leaves them with a big assignment: helping students keep up with their studies.

The challenge is likely to keep educators busy all school year as the flu hits in waves, officials said.

"We've seen some classes with half their kids out. That makes it very tough on teachers, trying to juggle classwork and makeup work for students," said Timothy Quinn, superintendent in the 5,400-student Methacton School District in Montgomery County.

"There are things that have to be done," Pemberton Township Superintendent Michael Gorman said. "Teachers have contractual hours, and then there are the hours beyond the school day for the best interests of the students."

Helping children recover academically after they've recovered physically is "going to be a continuing issue," said Michael Moskalski, superintendent and principal of Rancocas Valley Regional High, who anticipates a large number of sick children in the spring.

"This is a pandemic," he said. "There's a lot of unpredictability."

High absentee rates are not new, but this year, sickness began to take its toll just weeks into the semester.

There were so many absences among the staff and students at the Freedom Academy Charter School in Camden that it closed Monday. It will reopen tomorrow.

Two Philadelphia archdiocesan high schools, Archbishop Carroll in Radnor and Bishop Shanahan in Downingtown, closed in early October because of H1N1. They were the only schools in the Pennsylvania suburbs to cancel classes.

At Carroll, absenteeism peaked at 38 percent, and about a third of students were out at Shanahan. "Everything's back to normal now," archdiocesan spokesman Kevin Mulligan said.

Some districts, such as Philadelphia and Camden, have not been hard hit by flu. Tracey Williams, assistant director of health services for the Philadelphia School District, attributed the lack of cases to an education campaign launched in the spring.

The district encouraged parents to keep sick children home and emphasized proper hand-washing, coughing techniques, and other precautions, she said.

But in other districts, sickness has decimated classrooms. Kathleen Sheehan, a third-grade teacher at 290-student Aronimink Elementary in the Upper Darby School District, had 12 of 19 students absent at one point, and nearly all of her pupils have missed some time. In her 22 years at the school, she said, "I've never seen anything like it, not even close."

During the week of Oct. 19, Sheehan watched the progression of empty desks in her class. "I could see the flu moving across the room. The kids by the window were still there, but the middle of the class and toward the door - they were gone."

To cope with the lost time, an increasing number of students are taking tutorial and prep classes. They've gone online for assignments while home sick.

"We have teachers putting in more hours," Pemberton Township's Gorman said. "We have an extensive tutorial program at the beginning and end of the day, and teachers have Web sites where students can access assignments."

Sheehan made her ailing students homework and review packets that were picked up by parents or delivered through classmates or siblings, she said.