I also love to use sandtrays in group counseling. This is something I've experimented with off and on over the last year and I'll be honest, sometimes it works better than others. You have to know your audience. I did a sandtray group last week with a group of 3rd and 4th grade girls that have been in group together for about six weeks. I just asked them to create a picture of their world in the sand using the miniatures that I have available. I turn soft music on and let them work for about 30 minutes. After they have completed their picture, I give them a post-it and have the title their picture. Then as a group, we look at each tray individually. If the student wants to share their "story", I let them. Sometimes they don't want to and that is okay. If other students have a question, I let them ask. Students will become very engaged and interested in what others did and often times the questioning becomes a very bonding experience for the group when they open up and start sharing with each other about their trays.
Sandtray is a great resource for school counselors to use individually with students or in groups. If you are interested in learning more about sand tray, I encourage you to seek out training. It is something you need to have background knowledge about to use effectively.
Here are a few pictures of my girls doing their sandtrays last week.