In Massachusetts, a class of five-year-olds are learning this rhyme - set to the lullaby "Twinkle, Twinkle, Little Star" - so they know what to do during a school shooting.
Parent Georgy Cohen spotted the poem taped to a classroom chalkboard at the school in the city of Somerville.
She posted a picture online, writing: "This should not be hanging in my soon-to-be-kindergartener's classroom."
However, she made clear that she didn't blame the kindergarten for its approach, tweeting: "The school is doing exactly what they need to be doing, and I am glad for it. My issue is with the political & cultural factors that brought us to this sad state. Please talk to your legislators about the need for gun reform."