Van den Bossche, and Gijbels(2003) found there was no effect of PBL on declarative knowledge tests, but studies that compared PBL studente traditional curricula on measures of knowledge application and showed a moderate effect size favoring PBL students. Kirschner et al. cited the results of Patel, Groen, and Nor- tha man's(993) research. In this study, students from very different universities with different entering characteristics were fied compared(and indeed there is a self-selection bias in most scho studies of PBL). They were compared at a single time on Van a single task, but the PBL students did indeed transfer the stud hypothesis-driven reasoning strategy they were taught to new with problems whereas students in a traditional curriculum did not in use this reasoning strategy.