Addressing spirituality with children is different than addresing spirituality in adults, and it can start with mindfulness. I thought this article was great because it provides free, printable worksheets of activities to facilitate mindfulness with children. Parents could do this as well.
The Art of Mindfulness for Children: Mindfulness exercises that will raise happier, confident, compassionate, and calmer children. by Alisa Reddy, http://www.amazon.com/dp/B00IA0N4MI/ref=cm_sw_r_pi_dp_fmdctb0TVZ3JB