Sara Weis is a mother and elementary school teacher, as well as an experienced kids yoga instructor and teacher trainer. So she has a lot of useful suggestions for how to structure and pace a class while keeping kids safe and engaged.
But her biggest strength is as the creator of fun yoga-based activities. Her new book, Go Go Yoga for Kids: Yoga Lessons for Children has dozens of games and activities: Yoga Bingo! Princesses and pirates! Not to mention the four seasons, birthdays, the Olympics, and trips to the farm and circus. (Although I suspect one of the most popular themes might turn out to be the "Quick-and-Easy No-Time-to-Plan Kids Yoga Lesson.")