(NewsNation) — The tragic shooting at an elementary school in South Texas serves as a reminder of the ubiquitous nature of gun violence in the United States and the constant search for ways to stop it.

In the past, schools around the country have responded to high-profile mass shootings with a variety of measures intended to keep students safe.

None of these policies have served as a panacea. In fact, the risk for some tactics is that schools apply them without a full plan or real strategy, undermining their potential to help. Others point out that school shootings overall have actually declined since the 1990s — and that most students who die by gunfire are actually killed by guns in their own homes, far away from the reach of school policy.

We don’t know enough about the tragedy in Uvalde, Texas, to determine if anything would have stopped that tragedy. Yet as the nation debates school safety measures in the coming days, it’s worth reviewing some of the prevention measures schools have implemented.

ARMING TEACHERS

Many school districts have responded to school shootings by allowing teachers or other school staff to arm themselves in anticipation of potential shooters. In Texas, this option has been utilized by more than 170 school districts that, as of 2018, have armed school personnel. These districts are often in remote or rural parts of states; police response times are long in these regions.

Harrold Independent School District Superintendent David Thweatt offered his rationale for creating a plan in 2007 to arm some staff members.

“We take care of ourselves,” he said. “I don’t want to be anybody’s victim.”

Yet there isn’t any evidence that arming school personnel has yet been effective in preventing or stopping shootings. Using a firearm effectively requires training; there have been numerous incidents of professional law enforcement officials accidentally discharging weapons in schools.

SCHOOL SHOOTER DRILLS

Many American schools now drill their students on how to respond to an active-shooter event. These drills proliferated following tragic school shootings in Columbine, Colorado; Newtown, Connecticut; and Parkland, Florida.

During the 2017-2018 school year, 96% of public schools conducted such lockdown drills. By 2020, the majority of states required their public schools to conduct some form of active-shooter drill.

But recent research has shown that the drills may have led to a substantial increase in anxiety and stress for students who went through them. Also, it’s not clear if the drills have actually saved lives. In the Parkland shooting, the attacker reportedly made use of his knowledge of the drill at the school to plan his attack.

METAL DETECTORS

A 2011 study found the likelihood a student would walk into school with a gun dropped from 13.8% without metal detectors to 7.8% with metal detectors. But the debate has evolved over the last decade about whether they’re truly effective.

In an op-ed in the Washington Post, Carmen Black, an assistant professor of psychiatry at the Yale University School of Medicine, wrote detectors “…may indeed deter opportunistic assailants who impulsively harm our children with weapons,” but won’t stop a shooter with means and motive. 

The National School Safety and Security Services said despite limitations, there is evidence to build upon. It stated that detectors are one tool in the tool box schools can consider. 

The group’s president, Ken Trump, suggests school boards should avoid knee-jerk reactions to shootings that make headlines, and make sure implementing equipment such as metal detectors is part of a well-thought-out plan, not touted as a cure-all. 

SCHOOL RESOURCE OFFICERS

The number of school resource officers has increased from 34,000 in the 2003-04 school year to 52,100 in 2015-16. More recent data shows the percentage of schools using these officers, as well as police officers, continues to grow — particularly in the lower grades.

Like metal detectors, the effectiveness of these officers have also come into question in recent years, despite millions of dollars in funding. Newer studies on school resource officers suggest they do mitigate some violence, but also increase suspensions, expulsions and arrests, according to a report by Education Week. 

To address some of the shortcomings, the National Association of Secondary School Principals has offered recommendations to ensure the officer has the appropriate training and partnerships with school staff. 

Notably, it includes a suggested schools draft a Memorandum of Understanding, or MOU, that defines the school resource officer’s role and establishes clear lines between school discipline and criminal law enforcement.