Short Calculus

I think the first thing to note is that "constructivism" also has a mathematical meaning:
http://en.wikipedia.org/wiki/Constructivism_(mathematics)
basically related to the idea that to prove something true, it's not fair to (a) say "Assume it's not true", and (b) derive a contradiction. So, to prove that something exists, one has to "construct" it. The philosophical foundation for this theory is that "the statements an observer can make about the universe are divided into at least three groups: those that we can judge to be true, those that we can judge to be false and those whose truth we cannot decide upon at the present time".

There might be a nice way to relate this type of constructivism to the one you mentioned, e.g. through ideas like "[Constructivist learning theory] assumes humans can’t know the world as it is because there can’t be proved there is such a thing as objective cogniscence of the outside world." That's similar to the above statement which says, roughly, that it's not all black and white.

Maybe these philosophies can help us sketch a *third* type of constructivism, a "constructivist theory of motivation" or perhaps even "constructivist economics". A background question for such a theory would be: "How can you know what you like -- until you try it?". (Paraphrasing Francis the badger from "Bread and Jam for Francis".) But the deeper question is: why are people interested in X, Y, or Z?

For example, learning how to program is potentially "interesting" for people because programming can fairly quickly be used to make money. Maybe there are other reasons that it is more aesthetically interesting (e.g. it conveys a sense of power and control to the programmer). Mathematics has WAY LESS IMMEDIATE pay-off in terms of money. That said, according to a relatively recent study, "mathematician" was rated the NUMBER ONE most satisfying job in the US. See http://online.wsj.com/article/SB123119236117055127.html and http://www.careercast.com/jobs-rated/2009-jobs-rated-methodology

Perhaps a debatable finding -- no doubt everyone would put different priorities on the various factors, for instance -- but interesting as a collection of important factors nonetheless.

In particular, many the factors that this study considers could apply to people who are not professionals but are still students: physical environment, emotional environment, economic outlook, stress, and so on. My conclusion at the moment is that "learning design" should try to take these and other "life quality" factors into account. Is that "constructivist"? Maybe it would be, if people are allowed to define and update their own personal preferences as they go.