"Problem-based learning (PBL) is an exciting alternative to traditional classroom learning.
With PBL, your teacher presents you with a problem, not lectures or assignments or exercises.Since you are not handed "content", your learning becomes active in the sense that you discover and work with content that you determine to be necessary to solve the problem."
see http://www.studygs.net/pbl.htm

"One of the primary features of Problem-Based Learning is that it is student-centered. “Student-centered” refers to learning opportunities that are relevant to the students, the goals of which are at least partly determined by the students themselves."
see http://www.pbl.uci.edu/whatispbl.html

"Problem-based learning (PBL) is a student-centered pedagogy in which students learn about a subject in the context of complex, multifaceted, and realistic problems. Working in groups, students identify what they already know, what they need to know, and how and where to access new information that may lead to resolution of the problem. The role of the instructor is that of facilitator of learning who provides appropriate scaffolding of that process by (for example), asking probing questions, providing appropriate resources, and leading class discussions, as well as designing student assessments."
see http://en.wikipedia.org/wiki/Problem-based_learning