Not nearly as difficult as it may sound, Mystery Skype allows our students to connect with other students around the globe through a "20 Questions" type conversation. It involves critical thinking to figure out each other's location based on yes - no questions. You don't even have to use Skype to do it; we have used Google Hangouts successfully at Clear Creek in Mrs. Mulkern's class.
Awesome guide for Mystery Skype/Hangouts