c2263325_culty_Institute___What_is_PBL___WHY_
[WHAT:] Problems are complex and ambiguous, and require meta-cognition [HOW?] Select actual examples from the real life of the discipline that have no simple answers. Require students to analyze their own problem solving strategies. [WHY?] 
Requires the ability to use higher order thinking skills such as analysis, synthesis, evaluation, and creation of new knowledge.
Problem-Based Learning Faculty Institute - What is PBL?
WHY?