"Calm down" is a phrase that we all use, especially with kids when experiencing intense emotions. Here are some alternative phrases that just might yield better results, and an action plan to put them in place.
Classroom reward system- If the class shows great behavior, they will get to color in a letter tile of their choice. When every tile is colored in, the students will win that specific award. I just googled "Scrabble Font" and downloaded it for free. :)
Learn about Emotions with Build-a-Face Story Stones