Hi again,
I thought of other options for you! While I know you were thinking specifically of ritual work, as I said in my last post it is my (professional) opinion that ceremonial ritual work is too strenuous (and boring!) for most children. So here are a few more Earth Magick options for you that are more kid-friendly.
Reclaiming (<!-- w --><a class="postlink" href="http://www.reclaiming.org">www.reclaiming.org</a><!-- w -->) has two camps for families: Witchlets in the Woods (www.witchletsinthewoods.org) and Redwood Magic (www.reclaimingquarterly.org/web/rmfc). Both of these are great ways to a) introduce the basic concepts of magic to children where they can practice child-centered magic with other children and b) connect with other magical families. When my son is old enough, you can bet we'll attending one or the other.
I like to chant and I play music for my son every single day. Sometimes I play magical chants for him, so that they'll be familiar to him once he's older. Reclaiming has a few CD's that I love--you can look them up on Amazon; they all are great--but my absolute favorite Pagan/Goddess/Empowered Woman/Spiritual CD is called Goddess Chants by Shawna Carol.
I think for a 9 year old (is she growing up in a Pagan/Thelemitc household?) music might be an easy transition into ritual work. After all, we can cast a circle with song, and call in the quarters/elements with song, so why not learn some easy, accessible ways to do this?
Again, just some thoughts for you. Good luck!