I thought Dr. van Staden's comments about the merits of both C and I, along with his examples, we're right on. I, too, am skeptical when educators (in their enthusiasm and passion for constructivism) suggest that we cast aside anything having a hint of guidance, pre-specified objectives, or repeated practice.
Dr. van Staden's example (physics) pertained to a knowledge domain, but the same point can be made for skill domains. An example that comes to mind is the music lessons I took as a child--which I hated--which were taught in a strictly instructivist manner (the teacher selected the music, told me what exactly to do, what to practice, made no connections to anything that I enjoyed about music). Now, after 20 years, I have resumed lessons: I select the pieces I want to work on. If I hear something I like on CD, I ask the instructor "How do you think this musician did this?" and we work together to figure it out. But, one thing has not changed: I still must exercise great discipline in working through the practice exercises. The difference is that I don't mind because I have a clear idea of where I am going with it. (Okay, so the New York symphony may not be totally realistic--but let me dream!)
Perhaps constructivism helps us answer many of the questions about motivation, relevance, retention, and transfer (i.e., developing meaningful cognitive connections) that we have long struggled with. However, "instruction" or "instructivist strategies" help ensure we that the places we get to are useful, and it helps us learn from the expertise of those who have already asked and answered the same questions.