"What we've taught students in the real world — to not talk to strangers, to be kind and respectful to people — is not translating to the Internet world," said Ann Kirn, professional development manager who oversees i-SAFE programs in 12 states, including Florida.

Principals and teachers say students' online activities at night have worked their way into the school day, causing disputes between students and disruptions in the classroom.

Terry Humphrey, principal of Astronaut High School in Titusville, Fla., said the anonymity of blogs and chat rooms has allowed students to feel freer to gossip, make threats and spread rumors about each other. The results: a sense of fear and intimidation among victims who cannot identify their attackers.

"It doesn't come into the classrooms directly, but students come in with the baggage of what happened the night before; they're upset with each other, they're angry, and then it begins to affect school," Humphrey said.

Other school officials say the effects of social networking sites have cut even deeper, causing some students to miss school and others to become withdrawn, depressed and even suicidal.

"It's something that's affecting everyone, every family. It doesn't matter what economic background you are or what age group you are, it's a new arena and it's affecting everyone. The only way to fight it is through education," said Martinez.

That's a sentiment shared by i-SAFE's Kirn, who said students can't be expected to know the rules of the Web without guidance from adults.

"We need to provide them the tools, just as we do when they're learning to drive and getting their license," she said. "They need to be taught appropriate, safe and fair use of the Internet."