1Hmelo, C. E. &Ferrari. The problem-based learning tutorial: Cultivating higher order thinking skills.Journal of the education of the gifted, 1997(4):401-422.
2Problem-based learning,especially in the context of large classes [ EB/OL ] .http://www.chemeng.mcmaster.ca/pbl/pbl,htm.
3what is PBL? [EB/OL].http://edweb.sdsu.eduMrit/learning resource/ PBL/what is PBL.html.