W. Andrew Tillman is a displaced Texan who teaches high school economics in Tampa, Florida. The opinions expressed in this commentary are solely those of the author.

(CNN) My first day of teaching high school was September 11, 2001.

My educational training taught me that, on the first day of class, I needed to set a professional tone, establish ethos and create an inviting learning environment. But there was no training to prepare me to walk students through a terrorist attack.

W. Andrew Tillman

I learned a lot that day. I learned about remaining calm, the difficulty of explaining terrorism to a generation unfamiliar with it, and recognizing the need to allow my students and myself time to reflect and respond to what happened.

I have, unfortunately, had many opportunities since 9/11 to reflect on best practices for teaching students who may be traumatized by violence. In the wake of the tragedy last week in Parkland, Florida -- just a few hours from where I now teach high school -- I have been reminded of the lesson I learned on day one of my career. I heard my own concerns reflected in the voices of my friends, students and colleagues: what should we do next?

It has been suggested that one possible solution is to arm teachers in the classroom with weapons of their own to deter any would-be terrorists from another attack.

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