Recycle a soda bottle into a bird feeder.  Some inexpensive wood spoons, bird seed, a cord to hang it with and a tree to hang it in is all you need.

Then you and the host kids can watch the birds flock to the feeder!   Have the kids color pictures of the birds that visit.  Take photos, too.  Identify the birds and keep a little photo album of the birds that visit your feeder 🙂