Three years ago, it was rare for non-professionals to implement mobile applications. Even two years ago, building a working app was an intensive semester-long project. Today, implementing a mobile app can be a straightforward exercise. The challenge is to have good ideas for what to build. This course, taught by Hal Abelson at MIT in the fall of 2011, deals with how to pick project ideas and rapidly bring them to fruition through the prototype phase, how work as part of an effective rapid development team, and how to present your work in a compelling way.