The song is set to the tune of "Twinkle Twinkle Little Star".
A MA kindergarten class is drawing attention for using a lullaby to teach students about lockdown drills.
Skipper won't name the school where the poster is hanging, but said she understands why people might find it hard to accept.
A poster in a kindergarten classroom with the words to a rhyming song about a school lockdown is drawing attention on social media.
"Until something more concrete is done to keep school shootings and such from happening, teachers have to do what they need to do to help keep their kids (and themselves) safe", wrote one woman.
The post has already been liked and shared more than 60,000 times with many other parents sharing their outrage that the spate of school shootings had inevitably led to this.
Ms Cohen came across the poem while touring the school her child will attend after the summer holidays.
A mom shared a sign in her daughter's kindergarten in Somerville, Massachusetts, which teaches children how to hide from active shooters.
Georgy Cohen, who took the photo, tells The Boston Globe it was "jarring". As she said: "These are the things they unfortunately have to do". Nine out of 10 public schools have students and teachers practicing lockdown drills, according to the National Center for Education Statistics.
Kindergarten-aged children are learning the alphabet, numbers, colours - and a nursery rhyme with instructions to survive school shootings in the United States. "I'm always wondering if her school is going to be next, if a school near me is going to be next".
"To be shocked by it is important". "To see that absurdity and horror and have that sick feeling in your stomach is important". She urged her followers to talk to legislators about the importance of gun reform.
"As much as we would prefer that school lockdowns not be a part of the educational experience, unfortunately this is the world we live in", the statement reads. "Students in Somerville and across the country know how unnatural this is", it continued.