Here are some resources for helping children become calm and centered.
Yoga
http://www.abc-of-yoga.com/yogapractice/cat.asp
Resource books on yoga
Wiertsema, H. (2001). 101 Movement Games for Children: Fun and Learning with Playful Moving. Alameda, CA: Hunter House
Chryssica, M. (2006). I love Yoga. New York: Dorling Kindersley.
Garabedian, H. (2008). Itsy Bitsy Yoga for Toddlers and Preschoolers: 8-Minute Routines to Help Your Child Grow Smarter, Be Happier, and Behave Better. Cambridge, MA: Da Capo Press
Mainland, Pauline (1998). A yoga parade of animals. Boston: Element Children’s Books
Purperhart, H. (2007). The Yoga Adventure for Children: Playing, Dancing, Moving, Breathing, Relaxing Alameda, CA: Hunter House.
Purperhart, H. (2008). The Yoga Zoo Adventure: Animal Poses and Games for Little Kids. Alameda, CA: Hunter House.
Bersma, D. & Visscherm M. (2003). Yoga Games for Children: Fun and Fitness with Postures, Movements and Breath. Alameda, CA: Hunter House.