One of my favorite books on self-regulation is Listening to My Body by Gabi Garcia a school counselor. It is available in English and Spanish and learn more about the author at listeningtomybody.com/ This engaging picture book introduces children to the practice of listening to their bodies which is the first step to developing self-regulation. My students love the "horse lips" strategy where you take a deep breath in through your nose and blow out through your lips like a horse. It can change someones brain from being mad to silly in a few seconds. It is loaded with ideas so I frequently use it in 2 sessions in both individual and small group sessions. It will be one you use frequently!