Disputes about the impact of instructional guidance during teaching have been ongoing for more than a half century. On one side of this argument are those who believe that all people--novices and experts alike--learn best when provided with instruction that contains unguided or partly guided segments. On the other side are those who believe that…

Enthusiasm for problem-based learning (PBL) is widespread, yet there exists little rigorous experimental evidence of its effectiveness, especially in K-12 populations. Reported here is a highly controlled experimental study of PBL in a middle school population. Between- and within-subject comparisons are made of students learning the same material…