A kindergarten class in Somerville, Massachusetts has a nursery rhyme poster in the melody of "Twinkle, Twinkle, Little, Star" to prepare for an active shooter situation.
The poster became viral after Georgy Cohen tweeted a photo of it on Wednesday.
"That should not hang in my soon-kindergarten classroom," Cohen wrote.
"Lockdown, Lockdown, lock the door, turn off the lights, do not say anymore," reads the rhyme. "Go behind the desk and hide, wait until it's safe inside, Lockdown, Lockdown, it's all done, now it's time to have fun!"
The nursery rhyme was considered "disturbing" by many online. and considered "necessary".
"It's a pity that our children have to learn this, it's terrible," a parent
After this year's parkland in Florida, school shootings that killed 17 people and the school in Santa Fe, Texas In which 10 people were killed, schools at all levels had to plan and prepare for the worst-case scenario
"I think the training is perfect, and I think the schools are doing exactly what they are doing to make sure that our children are protected, "said another parent.