Dedapolis is a site where students can get practice with important concepts through a (hopefully) entertaining game. They can create characters, explore the city, face random encounters (that they can defeat through answering questions about concepts they're learning), and upgrade their characters and equipment. Their teachers can give them XP for participation in class, which they can use to level up their characters and get more powerful.
Note that at the moment Dedapolis is a very new site, and it's in a very early alpha state; most of the basic functionality is there at least at a rudimentary level, but most of what we plan for the site isn't implemented yet. In fact, if you're a teacher reading this, I'm honestly not sure how you found the site, since we haven't publicized it yet. Anyway, though, even though it's still in early alpha and incomplete, you can still use it; just be aware that it's missing a lot of features and there may be some bugs. (And we might be very slow in responding to your messages and requests, since we've got limited manpower and we're focused on improving the site.) More information about the site's alpha status here.