In spite of teaching in a constructivist style, I keep having concerns about constructivist approaches, having seen chaos ensue at times in my own classes and in others'. Plus having heard my daughter complain several times about teachers making them work on projects, saying, "why won't they just teach me!"
What follows is my interpretation along with quotes and references to the article. I would encourage you to read the article for your own interpretation.
The gist of the article's argument (that this instructional approach does not work) is based on how learning happens. To quote from the article: "Learning ... is defined as a change in long-term memory." (pg. 75) Meaning that when information moves from working memory, which can hold 7 or less things, into long-term memory, learning has occurred. And that this movement happens when there is a place for the information to go - when there is already some long-term memory in place already - some scaffolding in place to accept the new idea. The example of chess players being able to replicate complex moves from real games as they draw upon their experience/skill to quickly do so is given. But what then of being presented with problems for which there is no previous knowledge, no long-term memory to retrieve, no scaffolding in place? There's the rub for novice learners who have not been exposed to a concept, say the authors. And that's why instruction is key to prevent an overreliance on working memory (which can only hold a few items and which is lost when not "rehearsed") say the authors.
Additionally, the act of searching for information requires continual use of working memory, and when working memory is used for long periods it cannot be used to learn or to convert to long term memory.
The authors move next to looking at empirical examples concerning constructivism. The root of constructivism is that knowledge is constructed by learners and that learners need to construct their own learning in an instruction-sparse environment so that they discover the ideas on their own which then become their learning. The authors question here the withholding of information; traditionally constructivists give partial information allowing the learners to discover the rest of the information.
Here's the part that gives me pause and some trouble: the confusion by educators cited in the article between "teaching ... a discipline as inquiry...with the teaching of the discipline by inquiry" (p. 78) - and that the problem here is we (and our students) cannot be the researcher(s) with all the experience and background required to practice a discipline. (The part that gives me pause is that shouldn't there be some understanding of the research done by scientists? This is a real questioning of science labs done in middle schools and high schools everywhere.)
Moving to constructivist approaches a number of studies were cited supporting "direct instructional guidance" (p. 79) saying students learning purely by discovery "often become lost and frustrated, and their confusion can lead to misconceptions." (p. 79). The authors cite a study by Klahr and Nigam (2004) which found "Direct instruction involving considerable guidance, including examples, resulted in vastly more learning than discovery." (p. 79)
Another idea explored is cognitive load:
"free exploration of a highly complex environment may generate a heavy working memory load that is detrimental to learning...important in the case of novice learners who lack proper schemas to integrate the new information with their prior knowledge." (p. 80)
One antidote the authors suggest is worked examples for novice learners whereby they look over, in a guided way, how problems were solved. This works at least until the learners have a scaffold in place of long term memory and require less guidance.
This challenge to constructivism has left me reeling as an educator. I wonder about the examples used and the implementation. Leaving students unguided would not be my approach nor the approach of most of the educators I know. But does PBL, IBL, discovery learning, constructivism result in real learning that sticks? This article suggest that, at least for learners new to a concept, no, because these approaches rely too much on working memory and are based on taking the approaches used by experts and having student emulate these approaches - while leaving out the vast experience and knowledge these experts possess.
I need to see the other side more clearly - research on PBL, IBL and constructivism to see what that says about how (or if) it works.