Comet,
I dont know what you mean by case studies, but here is what I can tell you from my limited experience.
PBL students are assigned into groups of 8 or so. Every week or so, they are given a synopsis which includes many facts and a question/problem.
Its up to the students to extract the facts, list their ideas (hypothesis), and create a list the "things we need to find out" in order to prove/disprove the various hypothesis.
At the point they have the list of "thing we need to know", the group usually splits the work and goes about getting answers whichever way they please. The groups meet again to share their findings.
A "facilitator" (instuctor) joins the group a few times a week, for a few hours each, to make sure the group is following the intended path. Usually the facilitator will not get too involved, rather will let the group figure it out, unless they are waaay off.
This is supposed to help you learn "how to learn". Rather than spoon feeding you information, its up to you (and your group) to figure it out. So far, USC reports the board scores have gone up after they implemented the PBL system.
In all, I beleive the PBL system is designed to help create dentists who "can think", rationalize, analyze, and make good decisions.
