Every school has rules governing teacher behavior. Every state has laws against child abuse, and many specifically outlaw teachers taking sexual liberties with students. Every district has administrators who watch out for sexual misconduct by teachers.
Yet people like Chad Maughan stay in the classroom.
Maughan got in trouble twice for viewing pornography at schools in Washington state but was allowed to keep teaching. Within two years, he was convicted of raping a 14-year-old girl in his school.
Legal loopholes, fear of lawsuits and inattention all have weakened the safeguards that are supposed to protect children in school. The system fails hundreds of kids each year, an AP investigation found. It undoubtedly fails many more whose offenders go free.
State efforts to strengthen laws against sex abuse by teachers have run into opposition from school boards and teachers unions. In Congress, a measure that would train investigators and create a national registry of offenders hasn't even gotten a hearing. Few leaders recognize - let alone attack - a national shame.
"Instead of ignoring it or fighting it, why don't you get ahead of it?" says Ted Thompson, executive director of the National Association to Prevent Sexual Abuse of Children.
An Associated Press investigation identified 2,570 cases from 2001 to 2005 in which teachers were punished or removed from the classroom for sexual misconduct. The allegations ranged from fondling to rape. Reporters in all 50 states and the District of Columbia gathered the cases from state agencies with responsibility for teacher licensing.
Even accounting for population differences, states vary widely on how many teachers they discipline and how rigorously, the investigation showed. That reflects the patchwork nature of the laws and rules that aim to protect schoolchildren. Each state takes its own approach to background checks, fingerprinting and reporting abuse.
While states have taken halting steps toward accountability in recent years after decades of widespread neglect, there are still many gaps.
Some states check fingerprints against records only in their own states, not the FBI databases, so they miss offenders from other states. Others only check for violations when teachers are newly hired, missing veteran teachers who have run afoul of the law since they were first hired.
"You can fingerprint them all you want and nothing's going to come up," says John Seryak, a longtime Ohio middle school teacher who now trains teachers to spot when a colleague is abusing kids.
School systems also have made an attempt at weeding out wrongdoers. For the past 20 years, educators have shared information with other states about teachers who've run into administrative trouble.
The National Association of State Directors of Teacher Education and Certification created the list, and Roy Einreinhofer, its executive director, says protecting children is one of the group's top goals.
But the list has its flaws.
It only provides identifying information such as names, birth dates and Social Security numbers, nothing describing a teacher's past problems, leaving it up to a state agency or a hiring school district to dig deeper. Also, the list is not publicly available.
"There are some liability issues involved there," Einreinhofer says. "It just serves as a flag saying you need to check this person further."
Created in 1987, the list contains names of some 37,000 teachers who have had license problems, which includes all misbehavior, not just sexual.
Similar piecemeal efforts have often run into resistance, from lawmakers reluctant to tackle the subject, from teacher unions concerned with privacy and due process, and from school boards worried about court fights.
In Washington state, Maughan's case led to a law that clarified the definition of sexual misconduct and required school districts to share information.
Maughan had been suspended from one job for looking at pornography on school computers, but the district said only that he had used "poor judgment." At the second job, he was reprimanded for viewing pornography, and told administrators he had an addiction and was getting counseling.
In 2005, school employees found a paper bag containing a 14-year-old girl's red lace underwear and a sexually explicit note from her to Maughan. The teacher pleaded guilty to rape.
State Sen. Don Benton, who fought for the law that followed the arrest, said "we had tremendous resistance from the teachers union when it came to personnel files.
"We have to tell school districts, 'Look, you have a duty and a responsibility. As parents we are entrusting you with our children to take extra steps to ensure that the people you hire are safe."'
In Minnesota, the state school board association - allied with two church groups - has lobbied against a bill that would give victims of child sex abuse more time to bring civil claims. Schools, like churches, could be held liable if they failed to stop abuse that they should have known about.
"Schools have nothing to fear unless they either actively participated or covered up grave misconduct," says House Majority Leader Steve Smith, a Democrat pushing the measure.
Some union officials argue that the dangers are overstated.
"We're turning some of this now into a modern-day witch hunt and making it very difficult for teachers to have to say, 'I'm not one of those.' It's the wrong signal to send," says Steve Monaghan, president of the Louisiana Federation of Teachers. His state this spring declared it a crime punishable by up to six months imprisonment for a teacher to have sex with a student even if he or she is above the age of consent.
Advocates argue what's needed is a coordinated national approach. But there has been virtually no momentum there.
A report ordered by Congress and released in 2004 examined previous studies and surveys of teacher sexual misconduct and sent a troubling message. It estimated that some 4.5 million students out of 50 million in American public schools "are subject to sexual misconduct by an employee of a school sometime between kindergarten and 12th grade."
But that report, compiled by leading expert Charol Shakeshaft, head of the educational leadership department at Virginia Commonwealth University, was largely ignored.
This year, U.S. Rep. Adam Putnam, a Florida Republican, proposed legislation to create a national public registry of convicted offenders in schools, better training of investigators, and a national hot line for reports of sexual abuse in school.
It still hasn't received a hearing.
"It clearly is a problem and it appears to be growing," Putnam says, yet he is dismayed by the lack of concern. "You'd think the teachers association, the school boards, the principals - you'd think all of them would be on board to protect children."
Those who have fought for years to try to raise awareness of the issue see incremental gains, and the AP analysis found a steady increase in teachers removed from the classroom from 2001-2005. But advocates are despairing, not satisfied.
"We are mandated to send our children to school. Yet our schools are not being mandated to keep our children safe," says Terri Miller, president of SESAME, Inc., which stands for Stop Educator Sexual Abuse, Misconduct and Exploitation. "That is a horrendous problem, and that needs to be fixed."
She shares Putnam's enthusiasm for a new national registry and hopes for federal leadership that would force states to make their laws more uniform.
Others emphasize training as the best way to prevent abuse.
Some newly minted teachers graduate from college, have sex with a student and then say "What's wrong with that?" says Einreinhofer, at the national teacher certification group.
And more training is needed at the nation's public schools themselves.
For the past year in Rhinebeck, N.Y., administrators, teachers, students and parents have gone through a series of programs to recognize problem signs - teachers who get too personal with students, who "groom" students vulnerable to abuse, who test the boundaries by an inappropriate comment or touch.
The school community has been remarkably engaged and committed, says Bill Berard, the lawyer who taught the lessons.
Yet the training came as punishment. It was ordered as part of the settlement of a federal civil rights lawsuit, after former Rhinebeck High School Principal Thomas Mawhinney was accused of sexually harassing female students for years.
It often takes such scandals to inspire changes.
The AP investigation raised questions about an abusive teacher in Virginia who got a new job after being suspended for sexually abusing three girls. He molested two female students at the next school before the state finally acted on the earlier trouble and revoked his license.
Now, Virginia's Board of Education intends to seek legislation to tighten the background check and disciplinary process. "From now on, forever, we're going to ask ourselves, 'Can we do a better job?"' board President Mark E. Emblidge says.
The most powerful tool for change is money, says Thompson with the national child abuse prevention group.
That means dropping statutes of limitations that serve as barriers to lawsuits for all childhood sex abuse, he argues. Nothing motivates institutions more than the threat of paying out a big settlement.
Also, he says, it's the right thing to do: "Should somebody who raped a child be free and clear because the clock ticked?"
To victims' advocates, the problem is not just teachers who look the other way when one of their own misbehaves. It isn't only school prinicpals who choose a quiet solution to a problem. Lawmakers, judges, the media and even parents have all shown a great deal of reluctance to recognize and deal with sex abuse when it surfaces.
The nation needs to change its attitude toward teacher sexual misconduct, and child abuse overall, much in the way it changed its perspective about drunken driving in the last 25 years, Thompson says.
"Societally, we have a problem," says Mary Jo McGrath, a California attorney who has worked on teacher sexual abuse cases for three decades. "Our inability to think that kids might be in danger, our inability to think that the nicest teacher on the block might be an offender - those things keep us uneducated. I'm passionate that people wake up."