This from Brennan & Resnick, AERA 2012:

Part of this interest is fuelled by the growing availability of tools that enable young people to design their own

interactive media. But, more importantly, this interest is rooted in a commitment to learning through design activities, a constructionist approach to learning that highlights the importance of young people engaging in the development of external artifacts (Kafai & Resnick, 1996)."

Compare this to my comments on why we prototype in terms of my interpretation of Bret Victor (why waste all this CPU time simulating the world when the world is right at our elbow) AND variations on getting it out of your head so you can think AND a sort of Marxian idea of externalization and materialization.