Teachers and students roles - characteristics

In project-based learning, students work in groups to solve challenging problems that are authentic, curriculum-based, and often interdisciplinary. Learners decide how to approach a problem and what activities to pursue.They gather information from a variety of sources and synthesize, analyze, and derive knowledge from it.
Throughout this process, the teacher's role is to guide and advise, rather than to direct and manage, student work.

http://www.techlearning.com/db_area/archives/TL/2003/01/project.php