I'd like to comment briefly on the question/situation raised by Mike Vanhala [12 Apr 95] of Southern Illinois University. (Thanks, Mike, for your note! This isn't exactly an answer to your question, but your note "triggered" me to write.)
Although the philosophical perspectives of objectivism and constructivism may be of the "either/or" variety (either you are an objectivist or a constructivist--although I question even this from time to time), the application of a constructivist perspective to educational situations is not, in my humble opinion. I think the notion that instruction is antithetical to constructivism is a misconception, so is the idea that "discovery learning" is the only way to go. I also find lots of folks holding the misconception of equating the application of constructivism with motivation (i.e., another way of getting the learner to do what I want them to).
I also find it interesting how people in our field now want to label each other as constructivists or not (kinda like a religion). This always reminds me of the line from the Wizard of Oz: "Are you a good witch or a bad witch?" "Well, I'm not a witch at all!" When people ask me "what are you?" I usually say that I'm in-between an eclectic constructivist and a pragmatic constructivist!
To me, the key to a lot of this rests in a question posed by Seymour Papert in his recent book The Children's Machine: Does a [person] have a "right to intellectual self-determination?" (see p. 5). Although this question doesn't have a simple "yes/no" answer, I unfortunately feel that the school system, as a matter of public policy, would say no (assuming you allow me to personify the "school system"!) A person who wants to learn how to make optical lens will also see the value in having an expert show them the way (either in person, or through some medium). Even an apprenticeship model would have lots of situations that could easily be classified as "instruction." The difference here is that the instruction was deemed necessary by the student, not the designer. The instruction wasn't designed by someone for someone, but was negotiated through a complex social interaction. It's the same when I have a plumbing problem in my house and I try to fix it myself. Yeah, I might fool around trying to figure things how by taking stuff apart and studying it, but I will also be likely to go buy a "how to" book to show me the way step-by-step.
There is an old saying that I use in classes to help myself and others understand all this: "Life is a journey, not a destination." An objectivist focuses on the destination, but a constructivist focuses on the journey. (I've even prepared a little animation using Authorware to illustrate this.) It's easy to understand the extreme views of this metaphor: (1) engineers surveying the forest and laying down one road that takes travelers to one destination and (2) hikers wandering aimlessly through the woods--some make it out and some don't. My application of this rests somewhere in the middle (e.g., post some signs, make some trails and bridges, and have tour guides available, while all the while protecting the environment). When a group of travelers goes on a trip, the route must be negotiated in some way. I've come to see the methodology of rapid prototyping (as described by Tripp & Bichelmeyer, 1990) of giving "meat" to the abstract idea of "negotiation." (By the way, special thanks to Ron Zellner and Jim Zuhn of Texas A&M University for our discussions over the years with this metaphor.)
Papert, S. (1993). The children's machine: Rethinking school in the age of the computer. New York: Basic Books.
Tripp, S., & Bichelmeyer, B. (1990). Rapid prototyping: An alternative instructional design strategy. Educational Technology Research & Development, 38(1), 31-44.