HUNTERSVILLE, N.C. -- Ernest James Nichols remains in jail after his first appearance in court only took a few seconds.

But his case isn't the first time a teacher has been put behind bars charged with sex with a minor -- so Channel 9 went to local physiologist to ask why a teacher would do this.

Dr. Alan Bozman categorizes sex offenders two ways -- those who prey on children and seek jobs that give them access to children “and then you have people for, lack of a better term, are just stupid.”

Ernest Nichols, a teacher at Ranson Middle School, was arrested Thursday for allegedly having sex with a 15-year-old girl, although she was not one of his students.

We were there as police confiscated video-tapes from his Huntersville home on Thursday.

His case is one of about 10 in our area this year alone where teachers have been arrested for allegedly having sex with minors.

Dr. Bozman said some teachers flirt with students, students may flirt back and it can escalate.

“I think boundaries do get blurred,” Bozman said.

He says teachers who start relationships don't necessarily think what they're doing is acceptable or legal.

“You know what your obligations when you make this decision. You make a very conscious decision; nobody is doing this out in the open. That tells you they know they have something to hide,” Bozman said.

In one recent case, police say a Smith Academy teacher who was taking advantage of a young student gave that girl a cell phone. Her parents noticed the phone and called police.

“Things like giving a student a cell phone, that’s totally inappropriate and crosses the boundary immediately,” Bozman said.

Bozman says parents and other teachers need to be watchdogs and if a teacher is paying too much attention to a particular student or looking for lots of one-on-one time -- something might be up.

“These are not creepy guys. 90 percent of the time these are people who know your kid, who know your family,” Bozman said.