The New Atlantis published a wonderful online article Shop Class as Soulcraft that reflects on our increasing removal from manual work that might cause us to become more passive "consumers" than "producers", certainly more removed from the process and materials of how things are made.
Manual work has long been devalued, but perhaps even more so in this increasingly computer-driven world. But Crawford has really put his finger on something here. This article is not just a nostalgic look at the handcrafts or work of the past, it also points to an important truth about work done with ones' hands - there are insights that come only from physical experience, and because the lessons are not fully conscious or verbal, the learning may be hard to pass on except through other physical lessons. Also there are practical experience lessons that can only be learned by doing, like the experiences he cites with the computer modeling program Hypergami:
"In our early work with HyperGami, we often ran into situations in which the program provided us with a folding net that was mathematically correct—i.e., a technically correct unfolding of the desired solid—but otherwise disastrous. Figure 7 shows an example. Here, we are trying to create an approximation to a cone—a pyramid on a regular octagonal base. HyperGami provides us with a folding net that will, indeed, produce a pyramid; but typically, no paper crafter would come up with a net of this sort, since it is fiendishly hard to join together those eight tall triangles into a single vertex. In fact, this is an illustrative example of a more general idea—the difficulty of formalizing, in purely mathematical terms, what it means to produce a ‘realistic’ (and not merely technically correct) solution to an algorithmic problem derived from human practice."
Hypergami is a free downloadable program. Maybe a good activity with your kids? It might generate some interesting discussion about theoretical and "real" knowing. Practice with 2D to 3D conversions will also help stretch the spatial skills of some students.