RT Journal Article SR Electronic T1 Problem-based learning makes a difference. But why? JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP 61 OP 62 DO 10.1503/cmaj.071590 VO 178 IS 1 A1 Geoffrey Norman, PhD YR 2008 UL http://www.cmaj.ca/content/178/1/61.abstract