Gilbert, Ben. "Designing Edutainment the Valve Way: Make a Good Game First." Joystiq. 21 June 2012. Web.
Describes an ongoing project by Valve (a game publisher) called Steam for Schools. The basic idea is that commercial game makers create edutainment versions of their own games.
Refraction. Center for Game Science, University of Washington. Web.
This game is designed to teach students how to use fractions (in math). The game design is particularly compelling because it also gives feedback to the developers about how students are solving the game's puzzles.