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!

Cohen snapped a photograph of the sign, which included cartoons to go along with the sing-song directions, and posted it to Twitter.

“This should not be hanging in my soon-to-be-kindergartner’s classroom,’’ Cohen tweeted.

As of Thursday morning, it had been shared more than 13,000 times, as people discussed measures that have to be taken to help protect children in the wake of school shootings across the country, including recent massacres in Santa Fe, Texas, and Florida.

“It’s jarring,’’ Cohen told the Globe in a telephone interview Thursday. “When I was in kindergarten, we had fire drills. It was different — we didn’t have these same types of threats.’’

Cohen, who said the tour was part of a district-wide event for parents and children to get a preview of the schools they will attend after summer vacation, didn’t want to name the school where she saw the poster.

She said she doesn’t begrudge the school for having it, however — she was pleased to see that the teacher is taking steps to educate students about what to do in the event of an emergency.

But reading the words in a way that was playful, like a nursery rhyme, and seeing the multicolored letters, felt somewhat dystopian.

“These are the things they unfortunately have to do,’’ Cohen said. “I get it.’’

She added: “Part of their job is to educate and keep my kids safe and I feel confident they are going to do both of those things to the best of their ability.’’

In a joint statement to the Globe on Thursday, Somerville Mayor Joseph Curtatone and Superintendent Mary Skipper said as much as the city would like for lockdown drills not to be part of students’ educational experiences, “unfortunately, this is the world we live in.’’

They agreed with Cohen’s initial assessment of the circumstances, calling the need for lockdowns “jarring’’ for students, educators, and families.

“Students in Somerville and across the country know how unnatural this is, as evidenced by their vocal leadership and advocacy this year in response to continuing school shootings,’’ the statement said. “Just like school fire drills, lockdown drills have sadly become a common practice in schools, and educators do everything they can to reduce students’ anxiety and stress.’’

The statement said the poem is an example of how one teacher used a rhyme to help younger students remember to stay calm and follow steps during a drill or real emergency.

“I think that this is a case where our educators are in a new reality, and they are doing the best they can across all different grade levels to ensure they keep students safe,’’ Skipper said in a follow-up phone interview. “We regularly do our lockdown drills, and for our youngest students you have to age-appropriately introduce them to it.’’

Skipper said the sign is not a requirement in kindergarten classrooms throughout the district and was made independently. She called it “creative’’ but said it “speaks to a loss of innocence.’’

When asked about the flood of comments on the tweet, Cohen, who posted the image, said she’s glad it’s eliciting a strong reaction because “you can’t normalize’’ school shootings.

“To be shocked by it is important. To see that absurdity and horror and have that sick feeling in your stomach is important,’’ she said. “Stay outraged. And if it gets somebody to do something — to give money to an organization or to call their representatives . . . then great, I think that that’s important.’’

Steve Annear can be reached at steve.annear@globe.com.