I suppose this is similar to the event which most commonly causes a lockdown: an armed intruder. The lockdown is organized, efficient. We keep certain materials in our classroom, ready and prepared: cardboard to cover the narrow slit of a window in the solid classroom door. Our classrooms are already kept locked as standard. When I started, I used to lock myself out of my own classroom a dozen times a quarter. I’m doing better now.

Materials? I mentioned the cardboard, right? So, that’s it. We shelter in place. We have a cupboard, a closet in my room where the air-conditioning unit is housed. Sometimes I catch myself estimating how many students I could hide in there. Perhaps I should find out. No more than eight, I think. Where would the others go? My classroom is on the second floor, a flight of stairs off the ground, and the windows open no more than four inches.

The lockdowns are infrequent, no more than two practices a year, usually. I put up the cardboard, keep my 22 to 32 16-year-olds and 17-year-olds silent, or as silent as I can, and wait for the all clear. It’s routine. It’s routine to prepare for an active shooter. Routine to prepare to push a class roster under your door, confirming how many survivors you have in your classroom. To wonder which troubled kid might crumble so much, be so full of loathing that today is the day they pick up their family’s gun. You wonder what else you can do to prevent it. You call home, keep in contact with parents, try to connect with the seemingly silent students, the ones who don’t care enough, or who care too much. They’re all your kids. You watch them everyday. You carry them in your heart. They’re your first thought in the morning, and your last thought at night. You hope that it won’t be one of your kids. That it won’t be because you never took the time to notice their needs.

You do what you can. You do everything you can. It will not be enough.

The lawmakers who can do something. Are the ones who will choose to do nothing, because that’s what they’ve always chosen. Because they don’t even do something when 4-year-old and 5-year-old children—whisper it— white 4- and 5-year-olds are killed.

So you know. You know that every year, when the angry sun is beating down on the softball field, when the new intake of baby-faced freshmen scuttle through the corridors, when last year’s juniors embrace you, excited to finally see the finish line. You know. You check to see if the closet somehow has a Narnia-like door inside, extending into a magical safe world. Whether you can do anything other than move your desk to create a better barricade and choose who you might save.

Because it’s never if. It’s when.