I love yoga very much and by accident I found that my kids love it as well...I have two boys, both before the age of 6, who are both of them really really active, energetic and perky beyond words. After one crazy afternnoon, weeks ago, I thought, instead of running around with no purpose destroying the house why not tame them with some yoga, some kids yoga. And it actually worked a lot, which why I try to practise it with thwm every other day. They find it hilarious and funny and they seem to have the best time...I found this card the other day, which has the first basic positions of yoga , all suitable for kids.
We all know more or less how important is yoga to our health. In case you are not aware to the subject here there is an extensive chart of all the physiological, psychological and biochemical benefits of yoga.
Almost the same benefits are applied to kids as well. In this article from Parents it is very well and thoroughly described how children, by practising yoga will gain apart from a healthy and strong body, also confidence and better concentration.
My boys loved it and I hope your children will do as well.