Teachers give experience points, badges and other incentives to keep affirming and rewarding students.
Mozilla is in the process of creating a badge tool around 21st century skills, and it is an exciting preview to the potential of badges. I don't know about you, but I do like getting badges and rewards on Foursquare and Empire Avenue. This is all very similar to other video games, where student characters are rewarded better equipment, accolades, and characteristics. Students might get the "Perseverance Rank 1," "Helping a Teammate," or the "Computer Search Term Guru" badge. They might get experience points to use to purchase "virtual equipment" for their avatar. These points aren't actually used in their content grade per say. In fact, students do need grade points to feel rewarded. Students in a GBL unit get rewarded for demonstrated 21st century and other skills through a variety of methods to celebrate all kinds of success and to keep students engaged.