Summer campers thoroughly occupied
The idea is to probe the pellets for the mice or bird bones and attempt to reassemble the skeleton to find out what the owl has been eating. Owls eat prey whole but their stomachs can't process fur, feathers and bones so those parts build up akin to hair balls in cats and the owl spits them back out every couple of days. The resulting pellet is less disgusting than it sounds though. I've seen even squeamish kids get over it quickly and become enthralled by the tiny little bones hidden within.
Interested? You might try the following products.
For beginners: Student Owl Pellet Kit*
Bulk for groups: Barn Owl Pellets, 15 Pack*