There is an argument to be made for having a trained, armed guard at a public school as a protection against invaders. There is none to be made for letting teachers have firearms in public school classrooms.
The hysterical anti-gun lobby need not create any false fears regarding teachers carrying loaded weapons in classrooms. The concerns are real, and obvious, enough. That is not because guns are evil or awful things. They are not. It is because the risks inherent in introducing firearms into that environment outweigh the potential benefits.
Even the best-trained teachers have off days. The classroom is a high-distraction environment. One forgetful moment - setting the gun on the desk, failing to snap the holster or lock the drawer, forgetting to engage the safety - could end in tragedy. The odds of that happening would be far greater than the odds of a teacher stopping an intruder.
A school classroom is not at all like the home. Gun owners can and usually do teach their children to respect firearms and handle them safely. How many children in a public school classroom will have been so instructed? How many teachers, even if trained, will properly store their guns 100 percent of the time?
No, the classroom is no place for loaded firearms. That is not to say that schools should be weapon-free zones. Ensuring that some school personnel are trained and armed is an idea worth pursuing. Letting teachers carry guns in the classroom is not.