A Massachusetts kindergarten class is drawing attention for using a lullaby to teach students about lockdown drills. Taped to the classroom's chalkboard is a rhyme set to "Twinkle, Twinkle, Little Star," rewritten telling students what to do if there's a shooter. Parent Georgy Cohen noticed the poster while visiting the Somerville school. She took a photo and posted it on Twitter, writing, "This should not be hanging in my soon-to-be-kindergartener's classroom."

Her post had been shared more than 18,000 times by Thursday afternoon and drew hundreds of comments. Many said it's disturbing. Cohen told The Boston Globe the poster was "jarring," adding that students didn't have to deal with those types of threats when she was in kindergarten.