Whatever it is, it seems to be happening everywhere.

Permian High School in Odessa, Texas, was immortalized in the film "Friday Night Lights" for a rabid preoccupation with football and students' predilection for risky behavior.

Now, Permian has joined a long list of public and private schools receiving notoriety of a much darker sort.

Five of the school's staff have come under investigation for alleged inappropriate relationships with students in one of the largest school sex scandals of its kind. One teacher was cleared. Another committed suicide after being questioned.

Across the nation, lurid reports of sexual contact between students and teachers, administrators and coaches have surfaced.

Just within the past week, a female special needs teacher in Philadelphia was charged with having sex with a 14-year-old male student.

A teacher in Joplin, Mo., was accused of emailing nude pictures and having sex with a 16-year-old boy.

In Arizona, a male teacher was charged with sexually assaulting two girls, 15 and 16 years old, in his home, and filming them in various states of undress.

While sexual predators undoubtedly constitute a tiny fraction of the country's roughly 80,000 teachers and school employees, allegations of rapes and sexual assaults by adult staff members are gaining increased attention from lawmakers and child safety advocates.

"It's a small minority among a vast number educators who abuse children," said Terri L. Miller, president of Stop Educator Sexual Abuse, Misconduct and Exploitation, which lobbies to protect students and offers advice to victims and families.

"Unfortunately, this minority works in a profession where they can affect the lives of many students. It's a target-rich environment," Miller said.

The concern is shared by Paul Toner, head of the Massachusetts Teachers Association, who said his organization has no tolerance with abuse of any kind.

"We deplore any instances of educator mistreatment of students," Toner said. "The MTA believes that even one confirmed case is too many, and every allegation must be dealt with quickly and with full adherence to the law."

Consider the Attleboro area cases:

In January, Jeffrey Nichols, 47, principal of Attleboro's Grace Baptist Christian Academy and assistant pastor at his church, was charged with sexually molesting a student at the private school from seventh grade, when she was 13, until last year. Nichols, who was fired from his job, has been indicted by a grand jury.

Last month, Brian McBride, 31, a North Attleboro Middle School guidance counselor, was charged with statutory rape and other offenses for allegedly having sex with a 14-year-old female student and sending sexually graphic texts and photos to another girl. McBride, who was also fired, is awaiting trial.

Last week, former Attleboro High School teacher Christopher Defraga, 37, was charged with rape and assault and battery on a female student in 2008. Defraga, who left the Attleboro School Department that year after his Massachusetts certification expired, has denied the charges and said the sex was consensual and occurred after she graduated. Defraga has been placed on administrative leave from the Providence school system, where he now teaches.

Few statistics are available to document the extent to which teacher-initiated sexual abuse is a problem in public or private schools. The FBI's national crime database does not sort arrests for sexual crimes by perpetrators' occupations.

However, states such as Texas, where complaints of inappropriate relationships between teachers and students reportedly doubled from 2007 to 2012, acknowledge significant increases in such allegations.

Massachusetts education department records of 33 teachers who lost their licenses because of state action from 2009 to 2012 were not specific enough to detail whether they involved sexual allegations.

Some research suggests that sexual abuse at school - either by adults or fellow students - is more common than many people think.

A national survey of eighth- through 11th-graders conducted for the American Association of University Women in 2000 estimated up to 10 percent of U.S. school children are exposed to some form of sexual abuse - from lewd comments to unwanted touching - at some time during their school careers.

However, the survey addressed all perpetrators and was not limited to teachers who abuse children.

While reports of students abused by adults at their schools are becoming more frequent, many observers attribute the increase to more students and families reporting the incidents than in the past.

"These incidents have always been out there, but more are being reported today," said Kim Thomas, executive director of New Hope, which counsels victims of domestic and sexual violence.

"There are more supports now, and people are more apt to come forward and report," Thomas said.

Availability of counseling, greater sensitivity by law enforcement to sexual victimization and increased media coverage have all helped to remove taboos and make victims more willing to come forward.

SESAME's Miller blames the problem on inadequate vetting of teacher applicants by school districts and adults' use of electronic devices to reach impressionable students.

In too many cases, she said, adults have allegedly emailed nude pictures or texted sexually suggestive messages to students as a prelude to sexual contact.

"Technology has become a two-edged sword," she said. "It can be used to educate, but it can also be used to exploit."

Many school districts in Massachusetts, including North Attleboro, ban or severely restrict staff emailing and messaging to students.

While all states require background checks for teachers, the degree of vetting varies from state to state.

Massachusetts law requires school districts to conduct national backround checks every three years on all employees and volunteers. The requirement also applies to subcontractors who work on school grounds or might have direct and unsupervised contact with children.

Nationwide reforms to more closely monitor school staff and prevent those suspected of abuse from being quietly transferred to other districts is currently before the U.S. Senate.

The bipartisan bill, sponsored by U.S. Sen. Pat Toomey, R-Pa., and Sen. Joe Manchin, D-W.Va., would require periodic background checks of school staff, not just once prior to hiring.

In addition, school districts would be forbidden to facilitate the transfer or hiring of staffers by other districts if they have reason to believe they are guilty of misconduct.

However, the bill is currently stalled in the Senate, where it has encountered opposition as a new federal mandate.