You do not to a degree. To my knowledge there is no state that allows a person to carry a firearm legally into a school unless they are a cop. I know there has been a push nationally for teachers to be allowed to carry but not sure if any of that has passed.
I don’t see a problem with the book beyond the fact someone would desire to harm a child.
I know in Wisconsin it is illegal for anyone beyond law enforcement to carry a firearm onto school property. If you have a CCW you can carry on the sidewalk if you will outside of school property but not on to school property. We also have open carry in Wisconsin. If you don’t have a CCW you can’t be within 1000 ft of a school.
Ultimately I hate our children have to be taught to fear some whack job coming to kill them.
On a side note I did have conversations with my kids on what to do and where to go if someone broke into our home. A child’s first impulse is typically to go to mom or dad. My kids were taught were to hide and that me or mom would get there as quickly as we can. It never happened but there’s something to be said about being prepared.