PBL is Project Based Learning or Problem Based Learning. PBL is the most exciting, innovative and successful learning methodology. In the last 15 years, thousands of teachers have conducted PBL classes for millions of students. The results are simply outstanding, and all schools and educational institutions should start using PBL courses.
The Buck Institute for Education is an outstanding source for PBL, and a great place to start. Go the their link here.
You will be amazed.