This is something simple, but effective that I have used with high school students from Grades 8 through 12. A clear and easy way to keep calm in stressful situations, whether in anger or in fear. Talking about this three-step strategy and practicing it beforehand, gives students more power and agency over their emotions and responses in stressful situations.
Contained herein are both wallet-sized, poster-sized, and an in-between sized (what I call office-sized [used when working with the student in my office]) versions of this strategy, both in colour and black & white.
I find the wallet-sized the most useful to give to students to keep on their person —something they can take out and look at from time to time, and know that it is there should they need it in stressful moments. I also use the poster-sized on to put up in my office so that all students see it when they walk in. A practical strategy for us all, through and through.
My colleagues in elementary school have tried using this strategy and handout on their intermediate students, and have reported that it works well for them, as well. I hope it proves useful for you and your students, too.