"She gives hours to this program, and what she teaches these students is just amazing," Principal Michele Schulte said.
Piumetti has been the mock-trial coordinator for the past 10 years.
Her mock-trial team visits courtrooms in Los Angeles, where students meet with real lawyers who judge their mock cases, she said.
For 11 years, the school has participated in the county's mock-trial competition.
Students from schools around the county use the knowledge they have gained about legal proceedings and the judicial system to argue a court case against each other, Piumetti said.
"The students try out to be a lawyer or a witness," Piumetti said.
"They have to demonstrate knowledge of the case and think on their feet."
Since winning the award, Piumetti feels she has more of an incentive to work even harder and strive to be a better teacher, she said.
But she admits she wasn't expecting to win.
"I was shocked," she said. "I put in an e-mail to ask if it was real. I'm very proud and I'm very emotional about it."
Adrienne Qasabian, a senior, is on the mock-trial team. She has known Piumetti since she was a sophomore in her world-history class.
"We have the best and the brightest involved in mock trial," the 17-year-old said. "I think law and the art of argumentation teaches you to channel your argumentation, to use the English language to say what you want to say and put your own perspective on things. I think that's the most important lesson I've gotten out of mock trial."
Alex Jacke, 17, wants to pursue a career in music, but he also has an interest in criminal law.
Alex, who has been in mock trial since he was a junior, credits Piumetti for helping him develop an interest in law.
"I felt that the [award] was well deserved," Alex said.
"She is very dedicated. The mock-trial team is made up of basically all of the leaders of the campus who are involved in various activities around school. We've learned so much with what goes on in the courtroom."