Palo Alto High School has invalidated the results of 112 final exams in Algebra 2 after two teachers noticed irregularities in the scores, Principal Kim Diorio said today.

After investigating, "We were able to determine that there were text messages and photos of answers to the final exam sent between students," Diorio said in an e-mail to families this week, notifying them that scores had been invalidated.

Students were given the choice of retaking the exam Tuesday, June 10, or leaving their algebra grade as is.

Looking into the exams, teachers noticed many students had provided answers without showing their work and a pattern emerged of students finishing the test in record time, Diorio said.

"It's a two-hour exam that reportedly some students finished in under 30 minutes -- this triggered a red flag," she said.

One of the teachers questioned several students and students reported to him that a picture of the test had been taken and distributed.

"Unfortunately, we were not able to determine specifically which students were involved with this breach," Diorio said.

"Since this is a discipline issue, it wouldn't be appropriate to divulge other details regarding 'suspects' or consequences for students in this matter," she said. "We can share that we conducted a thorough investigation and, unfortunately, we've had difficulty in specifically knowing how many students were directly involved with cheating in this specific incident."

Diorio said the investigation is being handled by Dean of Students Craig Tuana, and students or parents with any knowledge of what happened were asked to come forward.

In her message to families, she said, "We apologize for any inconvenience this caused, and we thank all of the students who took the exam honestly and truthfully."