The answer to the titular question depends on a) your definition of “project-based learning,” and b) your methodology for measuring success.
In a just-published, comprehensive literature review, MDRC takes 84 pages to say: “we can’t really answer the question, because we don’t have consistent definitions or consistent methodologies.”
Without a common set of PBL design principles, it is difficult to use the existing body of research to draw conclusions about PBL’s effectiveness. (p. 53)
More rigorous evidence is needed to confirm whether PBL is a better approach to prepare students for college and career than traditional teacher-directed methods. (p. 55)
That’s a frustrating answer.
If you love and believe in PBL–and, more than most pedagogical theories, PBL really has true believers–you’d rather have a ringing endorsement.
If you’re a skeptic–check out Kirschner’s emphatic rejection here–you’d like this idea put to bed once and for all.
In this review, however, the authors make clear that until we agree what PBL really is (and, what it isn’t), we can’t coherently measure its effectiveness.
What Should Teachers Do?
In the absence of a clear research answer to this question, I have two suggestions.
First: teacher experience matters. If you and your colleagues have experience teaching both PBL and direct-instruction curricula, and you’ve had good success with one or the other, then draw on that experience. As long as you’re being honest with yourselves, and keeping good records, then your experience is–for now–at least as good as any other information we’ve got.
Second: rely on useful principles from cognitive science. Does PBL help your students pay attention? If yes, that’s good. Does PBL decrease their motivation? If yes, that’s bad.
Quite often, for instance, I find that PBL curricula overwhelm students’ working memory limits. If so, then it doesn’t matter that the curriculum ought to work, or was designed by experts, because it’s overwhelming working memory.
In other words: if the curriculum sounds upliftingly progressive, but it violates basic principles of cognition, then put the rubric down and step away from the authentic question.
Every curriculum must fit with the way that students’ brains work–including a PBL curriculum.
(In case you’re wondering, “MDRC” stands for “Manpower Demonstration Research Corporation.” It was created by the Ford Foundation; its lumpy name was simplified to MDRC in 2003. You can read its history here.)