Heather Lynne Zeo reportedly ignored an important message from her Christian upbringing: Thou shalt not commit adultery.

Police said yesterday that Zeo, 37, a married math teacher from North Penn High School in Lansdale, admitted to having a sexual relationship with a 17-year-old student last month. She allegedly also left sexually explicit Internet and phone messages for another student earlier in the school year.

Zeo, a mother of three, posted 10 percent of $25,000 bail yesterday after being arraigned before District Justice Harold Borek on charges of endangering the welfare of children and corruption of minors.

Zeo, a Christian singer who has released two CDs - "Light as a Feather" in 2003 and "Musically Math" in 2008 - contacted the boys on Facebook, one earlier in the school year and the other last month, according to the affidavit of probable cause.

The teen who police say had sex with Zeo told police that he had received and accepted a friend request from Zeo on Facebook and that throughout the affair they would communicate on the site at night about the sex acts that they were going to perform with one another, the affidavit said.

"The facts really speak for themselves," Montgomery County District Attorney Risa Ferman said at a news conference yesterday announcing the charges.

"We're dealing with a teacher, and a teacher is in a very unique position of trust and authority in both the school and the community," Ferman said.

Zeo began meeting the boy in her classroom during her free periods, for "kissing and petting," when no one would be in the room, the affidavit said.

During the second week of May, Zeo told the youth they had to be more secretive because rumors were spreading around school that she was having an inappropriate relationship with a student, according to the affidavit.

So, police said Zeo drove her minivan to the Target parking lot in Montgomery Township on two occasions to continue their tryst, the affidavit said.

The boy told police that on the second occasion, he and Zeo had sex in her car, the affidavit said.

The school district contacted police after being tipped off to the affair, Ferman said.

The other boy told police that earlier in the year, he had about five conversations with Zeo that were sexual in nature and that at one point, she told him that she probably would have sexual contact with him when they were in a room alone together. She told him to come to her classroom but he never did, the affidavit said.

As school let out yesterday, reactions ranged from shocked parents to unfazed students.

"It wasn't that surprising," said Jeff Masters, a senior at North Penn High School, who went to Zeo for math tutoring. "She was more like a friend or a student than a teacher."

Jen, a 10th-grader at the school who asked that her last name not be used, said she found the fact that a teacher would use Facebook to communicate with students disturbing.

"I think it's kind of creepy," she said. "Once she left a post for one of my guy friends that said, 'Nightie night.' "

Manu Jaggi, the father of a 10th-grade student, was shocked to hear of Zeo's arrest.

"It's a little unsettling," Jaggi said. "The safety of the children is number one. But unfortunately, the problem is that you are hearing about stuff like this more and more in the schools these days." *