PBL is Problem Based Learning. It's where you have a patient case, either real or made up, and each week, you are given more of the picture as of the disease or patient care (labs, imaging studies, treatments, etc), then you try to figure out what is wrong with the patient. The disease is usually associated with what you're studying at the time (i.e. Glycogen storage diseases would have a PBL during Glycogen metabolism on a patient with a Glycogen storage disease). I think you have 3 weeks per case in Biochem and most classes don't have a PBL option, I think Biochem was the only one for first years. 2nd, 3rd, and 4th years are more involved w/ case studies and PBL. Maybe Feelgood or Jonwill can illucidate some of the details as to 3rd and 4th year. I know that 3rd year, Fall semester, you do clinics and then you do case presentations/work ups in smaller groups based on cases you see in clinic. Hope that helped.