I have three students in my morning lesson, each of whom is occupied in his or her professional life with a contrasting material: animal skins, laminates, and semi-conductors.
A great many of my students are occupied in the material world, in manufacturing in one way or another. Digital revolution or no, we still make lots of stuff, physical stuff, and ship it around the world and sell it and buy it. Britain may be painfully reshaping itself as an offshore tax haven and financial services specialist, where manufacturing is a small and diminishing fraction of national output, but most of the rest of the world still likes to get its hands dirty.
So we have handbags and shoes made of crocodile and ostrich skin, work surfaces and wall panelling made of laminates, and memory sticks which use semi-conductive materials such as silicon.
I also use what I like to call my materials, although the real value of the commodity I sell is sublimated to pure structure (grammar) and skill-training. I give my students hand-outs – newspaper articles, pictures, prompt-sheets – and we work the materials together in various ways; but in truth the activity is immaterial, getting sounds and concepts either fixed or temporarily lodged in memory. Much of what we teach will inevitably fade, and the language written in memory dissolve, as though it were writ in water (which, in large part, it is).
The hope is that some small permanent change is also wrought, in the material structures of the brain. Some skills, like riding a bicycle, merely atrophy with time. But either way we cannot tell. Unlike making handbags, or laminates, the inputs and the outputs are only approximately correlated.