Education is a promise to our children. It is heartbreaking when that promise is broken.

On a hill overlooking Interstate 81 in Harrisburg, PA, four miles from the eponymous river, stands Susquehanna Township High School, where hundreds of broken-hearted students, parents and teachers gathered on Sept. 23 to ask why.

Why have nearly 20 percent of the school district’s teaching staff resigned or retired since January 2012?

Why was an “inappropriate” sexual relationship between an assistant principal and a student not reported to police, even after several teachers came forward?

Why has classroom discipline eroded to the point that teachers feel unsafe and disrespected and students feel abused and ignored?

The scene at the high school, as reported by Julianne Mattera of the Patriot-News/PennLive.com, resembled a noisy pep rally. Except that instead of cheering for a team, the students and teachers were fighting for their futures.

“I’ve been reporting many times that I’ve been getting assaulted, harassed, and even death threats. And nobody has done anything,” said David Smith, an openly gay student.

“There was a young lady, a teacher, who contacted me because she was threatened, received terroristic threats against her and her child, and I contacted the school district, and they had not done anything until there had been that contact,” said township resident Peter Speaks.

To top it off, according to Mattera, the school board was about to reward this record by extending the contracts of two assistant superintendents until public pressure forced them to back off.

What caused this breakdown? Officials blithely blamed it on “demographics.”

“We’re dealing with a lot of parents who think that this district ought to be the way it was a long time ago, and it can’t be because of the demographic changes,” said district spokeswoman Susan Anthony days before the rally. In case the coding was too subtle, Anthony explained that half the district’s student population is minority and nearly one-third is eligible for free or reduced-price lunches.

The people, some of whom held signs reading “We [heart] our diversity,” were not buying it. “It’s not the demographics,” said Speaks, who is African American.

The excuse is not a new one. Poverty and race are often cited by anti-reform apologists as hard-wired determiners of failure. This analysis ignores the success of institutions like the KIPP (Knowledge Is Power Program) public charter schools. Eighty-six percent of KIPP’s student body qualifies for free or reduced-price lunches. Yet by the end of 8th grade, 96 percent of classes outperform their local districts in reading and 92 percent outperform them in math.

Instead of working to multiply these success stories, the education establishment has circled the wagons around failing high schools. In 2010, 1,550 of these “dropout factories” graduated three-fifths or less of their incoming freshmen, according to Grad Nation.

The citizens of Susquehanna Township are tired of excuses.

“I’ve had problem students all 16 years of my career,” said math teacher Neil Via, who retired in August. “That’s not the difference. The difference is how they’re being handled now….  No consequences.”

“This is like desks being thrown and doors slammed,” said Peter Frengel, an English instructor who now teaches at the independent Harrisburg Academy. “People are being assaulted.”

“All the great teachers have left,” said parent Kathy Marzari. “It’s the lack of discipline. Every year it gets worse.”

This is not merely a local issue. In 2002, President George W. Bush signed the No Child Left Behind Act into law. It provided a safety valve for children to transfer out of “persistently dangerous” schools.

Unfortunately, lax definitions and chronic underreporting have made enforcement a joke. In 2010, 690 teacher assaults occurred in the School District of Philadelphia, according to the Philadelphia Inquirer. But only half were reported to police. And only a tiny handful of schools were deemed persistently dangerous.

Adding urgency is the spate of mass shootings across the nation, many tied to mental illness. “These mass killings are the tip of the iceberg of a much greater problem causing daily repercussions in schools across the nation,” wrote child and adolescent psychiatrist William Dikel. “If schools are able to address students’ mental health issues successfully, it is possible that they might prevent future violent acts.”

Killers are not born, they’re grown. And too many of our classrooms have become fertile soil. It’s the worst of both worlds: troubled students do not get the help they need, but are allowed to disrupt the education of others.

The people of one school district have had enough. They demand answers and action, not more broken promises. They deserve nothing less.