The community held a candlelight vigil Tuesday in Murrysville Community Park to mark the return to normality. Students were also allowed into the school for the first time in a week to get textbooks from their lockers.
Fatima Ahmad told the crowd outside the school she found her packed lunch from last Wednesday still in her locker, stinking of decay.
"We should all open ourselves up, like I did to my locker," Fatima said. "We shouldn't let the bad things -- like my lunch -- stew inside of us and rot."
A 16-year-old, Alex Hribal, has been charged with slashing 21 students and a security guard in a crowded hallway. No one was killed but some of the victims were seriously injured.
The crowd cheered for Janet Boger, whose son Jared remains in a Pittsburgh hospital. She thanked those at the vigil for their support.
"The real heroes were your children and the staff in your school," Murrysville Police Chief Tom Seefeld told parents.