You could say that all words are abstractions, and therefore my statement is false because almost all teaching uses words... obviously this is not what I meant. Some interpretive generosity about where to draw the lines between what counts as abstraction or concretion in a particular context is required.

With that said, I actually think you could teach someone (say, who didn't speak your language) how to use a film camera merely by demonstration. It would take longer than if you could use words, but would be doable.

And I would argue that this kind of operational ability (with no explicit theory) is usually where the bulk of the actual learning goes on, and is usually what we mean when we talk about competence. Sometimes it's shocking the theory that really talented people don't have in a domain... I'm thinking of things like poker, competitive programming, even competitive mathematics. Obviously such people have some sort of theory, but it may be largely implicit, learned almost entirely by doing, and different-looking from the accepted or academic theories of that domain.