Do you like challenges? More specifically, do you like geographic challenges?Then I think you would be interested in learning about #MysterySkype. Why the hashtag? #MysterySkype is a Twitter hashtag that teachers have been using to set up connections between their classes. The challenge is for students to guess the location of the other class by asking yes or no geographic questions. There are also spin-offs to #MysterySkype such as #MysteryAnimal and #MysteryNumber. Anything can become a mystery — how about a #MysteryElement from the periodic table?