In the United States, 3,500 breaches of our public schools occur with a weapon of some sort every year. Some have called for armed guards or teachers. Unfortunately, these ideas will not be effective, and this is supported by the data. The police response after Columbine was quicker and the police actively attacked the shooter. The Virginia Tech police were on site in three minutes. Keeping an unauthorized person from entering the building for at least five minutes appears to be the key means of defense.
Most schools are not built with school security construction best practices. Too much glass or glazing, and or vehicle penetration ability. Public schools in Maryland could all be secured for as little as $20 per pupil using such features as bollards to stop vehicle penetration, smaller windows, bullet resistant glass, mantraps, cameras and metal detectors. Other states and school districts are doing this instead of enacting more laws, bans, and restrictions. They decided to expend their limited resources on proven deterrents as retrofitting the buildings. Security measures can be built with beauty and style, sometimes totally disguised.
Had Sandy Hook Elementary School been fitted with smaller window openings, the kids would have been given time. State and federal buildings have these precautions. Parents, grandparents, teachers, staff and students can make this happen by calling local state senators, delegates or school board members. It scares me to think that our schools are this vulnerable. The money that will be spent defending the new firearm law in court could have gone to these security measures.