Jill Westendorp, who graduated from Southwest High School in Minneapolis in 2000, told me that “there were doors all over” her school, which consisted of two separate buildings, and before the Columbine shooting, “most of them were unlocked” during the school day. Students could walk freely in and out of whichever door they wanted, and Westendorp said she was never concerned about violence at school. After the shooting, “they put electromagnetic locks on all of the doors that would only release if the fire alarm was pulled,” she told me. Students were able to enter and exit through just one set of doors, she remembered.

The safety measures that some kids experience can leave them with warped perceptions of what going to school is like. When Nicole Martin’s daughter started high school this year and asked for a new backpack, Martin, who graduated from high school in 2001, was shocked. “I was like, ‘But you can’t carry one?,’” she told me in a Twitter direct message. “My husband thought I’d sprouted a second head when I said that.” Martin was remembering the backpack ban at her own high school, East Carter High, in Grayson, Kentucky, which was first put in place after a shooting there in 1993, in which a teacher and a custodian were killed. When Martin’s daughter told her that she was, in fact, allowed to carry a backpack, Martin responded, “Oh, a clear one, right?”