You could say I am an expert on school security. With more than 30 years of experience as a textbook salesman, I made my living by calling on Illinois schools. I called on the Chicago public schools, the best and worst of the suburban public schools, the smallest of rural schools, the Catholic schools, and the private ones.

Hard to believe, but I actually began my career in textbook sales strictly as a school cold-call salesman. Without appointment, I would enter a school carrying my weighted down leather book bag and report to the main office. I would show my business card and introduce myself to the school secretary. In most cases, she would provide me with the names, room numbers, and planning period times of the department heads (i.e., math, science, history) I wished to visit.

I always made it a point to never disturb teachers and department heads while they were teaching, or in meetings. As the years passed, I began to develop strong working relationships with school department heads. Eventually, I even became fairly comfortable entering certain schools through their open side doors, bypassing the main office check-in altogether, and going straight to my desired department heads' offices.

Sometimes not following school entrance protocol was not the beast idea.

One time in particular, I have to admit, was rather embarrassing.  A Chicago high school principal denied me permission to see his department heads because "they don't see salesmen without an appointment." At the time, I already had several years of selling experience with these faculty members and knew they would be OK with me dropping by. Instead of leaving the building as per the principal's instruction, I ducked around the corner and went up the stairs to make my sales calls anyway. An hour or so later, two high school upperclassmen (who were probably ditching a class) almost ran me over in an empty hallway, one yelling to the other, "Hurry this way, the principal is coming!" So what did I do? Having as strong a vested interest in avoiding the principal as they did, I grabbed my book bag, and matched the speedy bad boys, stride-for-stride, to safety!

In my personal world of calling on schools without an appointment and, at times, stretching (or skirting) the school rules of entrance, the winds of change were heading my way -- and for painfully sobering reasons.  In 1988, a troubled woman named Lori Dann killed and wounded some defenseless students in a very well-to-do Winnetka Illinois elementary school.

A slow growing consensus began that day in Illinois schools: if it could happen in Winnetka, it could happen anywhere. With subsequent copycat school shootings, a growing climate of gun violence across the U.S., and the 9/11 attacks on the WTC in 2001, schools started becoming more and more proactive about their own security.

Over my 30-plus years in textbook sales, I witnessed an evolution in school security that pretty much transformed my cold-call selling into a much less effective selling of school books via phone, email and appointment.  Unlike when I began my textbook sales career, most schools had become impenetrable to my cold-call sales approach.

This was the case because many schools were beginning to lock all their doors, sometimes electronically. School buildings were equipped with doorbells, intercoms, security cameras, and had a strict appointment only policy for visitors.  Some schools posted no-nonsense security guards (sometimes police) just inside their entrance doors and would not even allow me access to the main office.  There were even some schools that hired aggressive security guards outside the schools, and in their parking lots, demanding to know if I was a parent, if I had an appointment, and the nature of my business.

Schools were taking security very seriously. When they were not stopping me altogether, they were slowing me down with metal detectors and scanning my driver's license.

So what, in my opinion, based on my wealth of experience of calling on schools, are the best ways to keep schools safe from potential serial killer attack?  To begin with, I can honestly report we are not protecting our small neighborhood elementary and middle schools with the same diligence as we do our high schools.  We need to change that.

That said, I think in order to best provide student safety, schools should lock their doors, consider metal detectors, and have viable emergency plans.  But most important of all, schools need armed security.  I write this because I believe there is no better deterrent to a would-be killer of innocent school children than an armed guard (or teacher). And speaking from the point-of-view of someone who has never owned a gun in his life, I have no problem with the adage, "Nobody stops a bad guy with a gun faster and better than a good guy with a gun."