A core tenet of the progressive/constructivist education creed is that students must construct their own knowledge. For this reason, according to the creed, teachers should not impart knowledge or provide explicit instruction. A teacher should merely be a guide on the side instead of a sage on the stage, as the rhyming slogans of the creed have it.
I was recently watching a video called A Private Universe produced by the Harvard-Smithsonian Center for Astrophysics two decades ago that casts doubt on the wisdom of the knowledge construction dogma. The video shows students who were asked to explain what causes the seasons and the phases of the moon. From Harvard graduates to bright freshman, the explanations were all wrong. In other words, all these students were laboring under misconceptions.
The lesson here is that constructing one's own knowledge in areas like science has a great potential of leading to false beliefs. Many of these students probably had received explicit instruction from knowledgeable teachers and yet tenaciously persisted in constructing their own false knowledge. The way to correct these misconceptions cannot possibly be more construction of one's own knowledge as mandated by the creed, but teacher-centered ongoing diagnoses of the many misconceptions and heavy doses of explicit instruction with constant student feedback.
Here is how the producers describe the video:
With its famous opening scene at a Harvard graduation, this classic of education research brings into sharp focus the dilemma facing all educators: Why don’t even the brightest students truly grasp basic science concepts? This award-winning program traces the problem through interviews with Harvard graduates and their professors, as well as with a bright ninth-grader who has some confused ideas about the orbits of the planets. Equally useful for education methods classes, teacher workshops, and presentations to the public, A Private Universe is an essential resource for science and methodology teachers.