A Bucks County middle school teacher has been charged with sexually assaulting two of his ninth-grade students after propositioning the girls over the Internet and on their cell phones.

Jeffrey Anderson, 23, of Philadelphia, was arrested last night and charged with crimes including involuntary deviate sexual intercourse, aggravated indecent assault, and criminal use of communications devices.

Anderson had been the building substitute at Tohickon Middle School in Plumstead Township. He has acknowledged his crimes, court records say, and has been dismissed by the Central Bucks School District.

Tohickon teachers and staff members were told of Anderson's arrest in a meeting with administrators early this morning before classes.

According to court records, Anderson admitted that he kissed, fondled and digitally penetrated the girls, age 15 and 14, inside the 15-year-old's house on a recent Saturday afternoon. He also engaged in oral sex with the younger girl during the April 30 meeting, the records say.

If convicted of the most serious crimes, Anderson faces a minimum five years in state prison.

The girls' parents recently confronted their daughters after learning their daughters had been communicating with Anderson by computer instant messaging and through Facebook.com personal Web sites, a probable cause affidavit said. The parents contacted police after the girls admitted having met with Anderson and engaging in sexual acts with him.

Both girls had been in Anderson's class, and had been messaging him outside of school for about a month. In some exchanges, Anderson told the girls he wanted to have sex with them, the affidavit says, and recently met with them in a Tohickon classroom and kissed them.

In an April 22 Facebook posting, Anderson pleaded with the girls to keep things quiet, the affidavit says.

"PLEASE . . . nothing that is said or done between the three of us can EVER be repeated to anyone else!!!" the message said. "Not your best friend, your diary, or any of those girls at school!! I could get fired, never become a teacher again. or go to jail. . ."

Five days later, after an explicit proposition to the girls on Facebook, Anderson allegedly added: "Hah . . . im so going to hell . . . I can't believe I hooked up with two 9th graders!!"

On Saturday, April 29, the affidavit says, Anderson was text-messaging the girls on his cell phone when he learned that the 15-year-old's parents would be away for the day. At about 4 p.m. he parked his vehicle down the block from the girl's house and met both girls inside, where they engaged in sexual acts.

A few days later, Anderson met the 14-year-old inside a Tohickon chorus room and kissed her, the affidavit said.

When confronted by detectives on Monday, Anderson admitted to having sexual relationships with both girls, and provided a 14-page written confession, the affidavit said.

The charges echo a 2003 case in which Ryan Newman, a popular young art teacher at neighboring Holicong Middle School, went to prison for at least five years after admitting to an affair with a 15-year-old student.

Newman was well-known among students for chatting online, and some even stopped by his apartment in Doylestown Borough to socialize.

Like many districts, Central Bucks has a general policy prohibiting offensive contact or relationships between students and employees, but does not specifically ban fraternization outside of school.

Contact staff writer Larry King at 215-345-0446 or lking@phillynews.com.