An American history timeline wraps around the walls of Jamie Sawatzky's cheerfully cluttered classroom at Rocky Run Middle School in Chantilly.

Sawatzky's seventh-graders began the year studying westward expansion and added each new topic to the timeline as they went. He hoped that by June, it would loop all the way round the room until it hit 1990, the year most of his students were born.

But a deluge of snow put a thick white damper on those plans. On Monday, it will have been 10 days since Sawatzky last saw his students -- and that was way back during World War I. First he'll give them a long-delayed exam and then race them through the Jazz Age.

"I guess I'll just play some music while they take the test," Sawatzky joked.

Although children in the area have been reveling in the unexpectedly long break, their teachers are scrambling to regroup to cope with a dramatically different school calendar.

Lesson plans are constructed carefully so that students reach certain milestones in time for standardized or national tests. Each lesson builds on another, so nothing can be skipped. That means that most teachers can't spend much time reviewing for children who have been staying up late and sleeping in.

"One week of snow break is equivalent to three weeks of summer," said Laura Feld, an algebra and Math 7 teacher at Rocky Run. "When they left me, I was about ready to give them a test on fractions. I know that they will have forgotten that."

For Pam Gwinn, chairwoman of the social studies department at Osbourn Park High School near Manassas, missing a week means the difference between interactive lessons and less-engaging lectures. For the unit on Teddy Roosevelt and the Age of Imperialism, she had planned a conversation among her students about how he might have reacted to terrorist attacks and Saddam Hussein's Iraq.

"I'm simply going to have to give them the notes," Gwinn said.

What she can't do, Gwinn said, is pack more material in. "Conventional wisdom is that with the 90-minute class period, you can cover twice as much information as with the 45- or 50-minute blocks," she said. "But children can only absorb so much information at a time."

Even in elementary school, teachers stick to a schedule. "We were in the middle of two novels," said JoAnne McKernon, a fourth-grade teacher at Waters Landing Elementary School in Germantown. "I wonder if they're even going to remember the story" of Charlie and the Chocolate Factory or The People in Pineapple Place.

McKernon plans to spend at least part of Day 1 reviewing, putting off a test on fractions. But she knows she'll have to let the kids talk about the snow and get it out of their systems. After a single snow day, McKernon gives her youngsters about 10 minutes to socialize and settle down.

"Monday, it's going to be a whole different story," she said.

Recognizing that area school districts are behind because of the snow, the Virginia Department of Education is allowing districts to decide whether to take the Standards of Learning writing test on schedule or delay it eight days. But Maryland officials said they cannot consider a similar delay for the Maryland School Assessment, which will start March 3.

"We are on an hour-by-hour schedule to meet federal deadlines," said Ronald Peiffer, a spokesman for the Maryland State Department of Education, "and it's going to be extraordinarily tight."

Nor will the College Board consider delaying Advanced Placement tests, as it did in 2001 for students who missed weeks of school in the flooded Mississippi Valley, College Board spokeswoman Jennifer Topiel said.

Seventh-graders don't take SOL exams, so Sawatzky's only worry is how to cover everything and keep it interesting. Coming up as a part of his unit on race relations in the 1920s is a lesson on the Tulsa race riot of 1921 that he particularly likes teaching because the episode is not well known.

"I don't want to chop it, but I'm looking at the calendar," he said. "I guess I'll have to pull some other stuff out."

Staff writer Theola Labbe{acute} contributed to this report.

Laura Feld works on her schedule in her classroom at Rocky Run Middle School in Chantilly.