Washington: Teachers, it is said, have some of the hardest jobs in the world. The hours are long, and the rewards often intangible. In addition to designing and executing lesson plans, grading homework and coordinating extracurricular activities, teachers are expected to be surrogate parents, offering children personal comfort and protection over the course of a long school day.

In recent years, teachers in the United States have also had to contend with a devastating reality: the increasing threat of school shootings.

School districts in many US states now allow certain teachers to carry guns in schools. Credit:Bloomberg

While gun violence in America has significantly declined since the 1990s, mass public shootings are on the rise, and schools are now viewed as vulnerable targets. One of the deadliest in history claimed 28 lives, including 20 children, after Adam Lanza opened fire at Sandy Hook Elementary School in Newtown, Connecticut, in 2012.

Last October, a gunman fatally shot nine people at Umpqua Community College in Roseburg, Oregon.