BLACKSBURG, Va. - Chemistry professor Joe Merola tried to give a lecture yesterday, but looking out at 100 Virginia Tech students' faces - and the sweatshirt he had placed on the seat of a wounded student - he could not do it.

"I lost it halfway through class," he said. "I burst into tears and had to turn it over to the counselors."

Students and staff paused twice yesterday, at the moments when a week earlier gunman Seung-Hui Cho opened fire in two campus buildings, killing 32 people and himself.

Then they returned to class for the first time since the shootings to seek solace in what used to be routine.

They found little was as they had left it.

Talking about the tragedy took precedence over class work, with volunteer counselors on campus wearing purple armbands, and a counselor in every class where a slain or injured student had been enrolled. Students and professors shared personal stories.

"We kind of talked and hugged. There were tears and stuff," said Paul Deyerle, 20, a sophomore from Roanoke who attended three classes. "It was good closure."

Yesterday was the first time since the shootings that Andrea Falletti had been near the memorial to the victims in front of Burruss Hall, which became a triage center for those shot at nearby Norris Hall. Faint, brownish bloodstains still marred the sidewalk.

"Every day, you wake up and you don't know what you should do. Everyone's like: 'Should we do something? Should we try to have fun?' " said Falletti, a 21-year-old senior. "You almost feel guilty smiling in Blacksburg."

Emotions spanned the spectrum of solemnity.

"We are seeing the resolute, the angry, the confused, and the numb," said Ed Spencer, the associate vice president of student affairs.

As many as 90 percent of Virginia Tech students returned to campus, and school officials said class attendance yesterday hovered about 75 percent. Many said the only way to cope was to get back to school.

"You could choose to either be sad, or cheer up a little and continue the regular routine," said student Juan Carlos Ugarte, 22. "Right now, I think all of us need to cheer up."

The day began in silence, a trickle of students emerging slowly from their dorms and forming a crowd of about 100 to remember the moment Cho began the rampage by killing two students in a dormitory.

Afterward, a group of students and campus ministers brought 33 white prayer flags from the dorm to the school's War Memorial Chapel.

By 9:45 a.m., thousands had gathered on the main campus lawn to mark the time of the second wave of killings, staring upward as a man in a Virginia Tech cap rang an antique bell 33 times, and students and staff released white balloons into the sky for each victim.

As the balloons drifted out of sight, the only sounds were tearful sniffles and the clicks of cameras.

Then 1,000 balloons in the school colors - maroon and orange - went up. Again, people stood in silence until they disappeared, reluctant to let go of the moment.

After a few chants of "Let's Go, Hokies," they headed off to class.

University officials said yesterday they had not yet decided the future of Norris Hall, the classroom and office building where most victims were killed. But it is unlikely that Norris will be used for classes again, provost Mark McNamee said.