This is a philosophy of education in which children learn by doing and experiencing. They explore and discover instead of being force fed information.
Much more on this topic can be found by exploring Google using keywords such as "constructionism", "education", "philosophy". One small start is here: http://mia.openworldlearning.org/constructivism.htm
Notice that Constructivism is not the same as Edutainment. See Edutainment? No Thanks. I Prefer Playful Learning
Alan Kay and his Squeak project have done a lot to make tools available to teachers who want to develop constructionist educational materials. Alan recently gave a keynote at EuroPython demonstrating how kids can learn constructively.
Also this wikipedia article on constructionist learning
One of the great pioneers of the practice, long before the term, was University of Pittsburgh's sociologist Omar Khayyam Moore, who built his "Edison Talking Typewriter" to teach two-year olds to read and write simply by reinforcing aspects of their spontaneous behavior.
Prof. Howard Peelle of the Education School at the University of Massachusetts has written about his experiments with APL in elementary school. The idea is to let children play a game, then learn to make simple adjustments to game play, and progress to full programming. IBM once sponsored a program to support APL for a whole elementary school.
There does not appear to be a single Best Computer Language for elementary school students, but most people agree that Basic doesn't come close. (Among software developers, the proverb is "Basic isn't.") APL, LISP, LOGO, Smalltalk, and several others have been proposed and tried. It would be useful to bring the resulting knowledge together. It is clearly impossible to settle the question based only on the stated preferences of adults who don't know all of the languages concerned, that is through rwars.