Everyone sits in a circle and one person starts by showing everyone a scar that they have on their body, keep it clean, of course.
Each person begins by telling the story behind the scar. After they are done, continue on around the group until everyone has had a chance to share an experience.
This is a great ice breaker because you will be able to see what activities, etc. that the kids are into because the scar usually will be a result of it.