A Massachusetts kindergarten classroom decided it was time to prepare students in the event of an active shooter lockdown. To help the young children remember what to do, they created a nursery rhyme set to the tune of the classic lullaby.

While touring a kindergarten in Somerville on Wednesday to get a sense of what to expect when her 5-year-old daughter starts school in the fall, Georgy Cohen took stock of the items one might typically find in a classroom for young kids.

Art supplies. Signs about how to wash your hands properly. A chart of the alphabet. Tiny desks.

And then something grabbed Cohen’s attention: On the wall was a set of directions for what children in class should do in the event of a lockdown drill, written in colorful and bubbly letters — to the tune of “Twinkle, Twinkle, Little Star.”

It read:

Lockdown, lockdown, Lock the door

Shut the lights off, Say no more

Go behind the desk and hide

Wait until it’s safe inside

Lockdown, Lockdown it’s all done

Now it’s time to have some fun!