It has been called a pragmatic response to a "very present danger". And it means that for many teachers and students across the US, masked gunmen breaking into their schools could become a regular part of life, with several states calling for frequent "gun attack drills".
Officials in states across the country have either tabled bills or passed new laws calling on schools to perform so-called "intruder" drills in a bid to better prepare their staff and students for the possibility of a mass shooting. Penn High School in Indiana even carried out a mock shooting in April, complete with fake blood and a body count.
The move comes in the wake of the shooting at Sandy Hook Elementary School in Connecticut, US, last December, which claimed the lives of 20 children, most of whom were aged 6-7, as well as six members of staff.
Speaking to TES earlier this month about how the community in Newtown was coping six months after the tragedy, Janet Robinson, the area's former superintendent of schools, said that she hoped people realised that if it could happen in her town, "it can happen any place".
From the start of the new school year, children in the state of Arkansas will be expected to take part in annual "active-shooter" drills, as they would a fire drill, after state governor Mike Beebe passed a law to that effect in March.
States including Louisiana, Tennessee and Washington are considering new laws that would require regular intruder or lockdown drills in schools throughout the year.
The reaction of parents and officials to such drills is mixed, but school safety experts believe that they are a pragmatic response to the problem.
The National School Safety Center, based in California, aims to help schools provide safe learning environments. It said that an "all-hazards training approach" was recommended.
"Drill and practice make a lot of sense," said the executive director of the centre, Ronald Stephens. "Practice drills coordinated with first responder agencies can be very valuable.
"While it is difficult to prevent all school crime, it is possible to prevent and minimise successive crises through good planning and preparation."
About 130 fatal school shootings took place in the US between 1999, when 12 students and a teacher were killed at Columbine High School in Colorado, and last year's tragedy at Sandy Hook.
The increase in the frequency of attacks has led to a boom in business for companies that offer schools and other public institutions advice and training in how to respond to gun attacks.
The Alice Training Institute, formerly known as Response Options, said that it had seen a dramatic increase in calls from schools to provide guidance, and it has been forced to expand its workforce. It does not perform "active-shooter" drills, opting instead to use the Alice method - Alert, Lockdown, Inform, Counter and Evacuate.
"We train teachers across the country in how to deal with an intruder, what to do in the first five minutes, and to advise that simply locking down the school isn't always the best option, that if you can evacuate you should," said the institute's vice-president, Marianne Alvarez.
"The fire departments have done an excellent job when it comes to fire drills and so the police forces need to get into schools to prepare schools for what is a very present danger."
Ms Alvarez said that even a small amount of training can prevent teachers and students from becoming "deer in the headlights" in the event of a gunman entering a school.