Each character also has hit points, just like in WoW, and you can lose hit points through poor classroom behavior or missing homework deadlines. If your hit points go to zero, you earn yourself a detention or some other sort of penalty. But your teammates can help you out, too. Warriors, with their large hit point pool, can soak damage, and priests can heal it back. Like this, teams are encouraged to work together and help each other learn the material. Mr. Young calls the whole system "World of ClassCraft" in honor of WoW, which it imitates.
How effective has this been so far? Mr. Young is quoted as saying that it's hard to tell if there's a straight correlation between game and grades, but there has been a noticeable shift in motivation. Students that acted bored or disaffected are actively engaged in the game and have begun to work much harder in class than they did before. As a former teacher myself, I imagine that's a big encouragement to Mr. Young.
One of the most difficult things about teaching is getting people engaged in the material, or getting them to understand why they're learning something that may not seem directly related at first glance. As an instructor, you might know that certain foundations need to be laid before you can move on to "the good stuff" material-wise, but sometimes students have trouble seeing the long game. Mr. Young seems to have hit on a strategy that is working for the time being, and I certainly hope we hear more from him and other teachers like him in the future. With all the doom and gloom reports about failing schools and universities, it's nice to highlight some places where teachers are finding success.
I wish Mr. Young and his students the best of luck!