Teaching first- and second-hand knowledge

I’m still ruminating on themes of “practice” and “mastery” I touched on in some previous posts. This blog is starting to serve as a “parking lot” for ideas that I hope to weave together into a more coherent form someday.

I’m not sure what exactly sparked off this latest thought, but I’ve been noticing the distinction between teaching first-hand and second-hand knowledge.  Teaching something we know first-hand is pretty obvious – I can teach a child how to tie a shoelace, or a colleague how to specify a statistical model. I don’t have to draw on external resources to provide the content, although teaching aids (pictures, text books, etc) can help embellish an explanation.

Secondary knowledge is something I don’t have direct experience with, and here it gets interesting.  Most of us adults (who aren’t professional historians) know something of the founding of the United States, the framing of the Constitution, the Revolutionary War, etc.  We can also tell these stories to our children, but how sure are we about the knowledge we’re imparting?  Telling any sort of cultural myth generally entails passing along a story or knowledge that one has not directly experienced; we serve as conduits for a communal story.

Okay, so far no problem – there are things we know directly (and teach/coach) and other things we pass along (such as historical narratives).  Now think of middle school science teachers.  Are they teaching primary or secondary knowledge? It’s an interesting question.  Many are probably generally well-versed in textbook knowledge (they may have even majored in a science), but to what extent have they internalized the knowledge as their own?  I could probably do a decent job of teaching a basic physics class, but I was never really a practicing physicist, and know little beyond the first year college course.  So what would I be doing, other than interpreting/explaining what was already in a text book? What would I add of my own?  And does it matter?

A while back a friend of mine asked me how to get rid of these whitish rings that had appeared on his dining table. I knew I’d read about those in a book on finishing, and sure enough I was able to look it up and respond with a remedy – try mild heat, and perhaps gentle abrasion with steel wool.  But I also warned him that I had never actually tried any of these remedies myself, so couldn’t vouch for them or for unforeseen consequences.  It was an unsatisfying experience.

In a similar vein, I’ve certainly read about wood movement (the tendency of wood to expand and contract along particular dimensions with varying humidity) and how to design for it, but I’ve never actually experienced, say, a panel blowing out of a frame or a drawer getting stuck in its casing.  On the other hand, I’ve both read and experienced what can happen if an off-cut catches the back part of a spinning table saw blade, or what a bowl feels like as it flies off of a lathe and into my face shield. I know that you shouldn’t brake around corners on a fast mountain bike descent, and I know why you shouldn’t do so (having done it and experienced the consequences).

So back to my question: when does it matter that a teacher possesses first-hand, experiential knowledge of a subject, versus largely second-hand, “received wisdom?”  We intuitively prefer the former, and I suspect there are varying degrees of the latter. That is, I was never a math major, but have a reasonable intuition about some aspects of middle- and high-school math.  I certainly know real-number algebra inside-out.  But – although I took a course in abstract algebra as an undergraduate – I know I don’t have the deeper connection to theories of algebras, how systems of domains and operators come together coherently. So I can help a high school freshman struggling with his or her algebra homework, but there are limits to what I can teach.

I’m starting to examine my own balance between first- and second-hand knowledge, both at work and in general life. It’s starting to feel like exploration – we go out and cover some territory, come to know it well, but hear from fellow travelers about what lies over the next hill.  Perhaps we even pass that folklore along to others, along with our own hard-won knowledge of familiar terrain. And we make judgments about risks – the consequences of mis-informing a fellow traveler about the safety of that frozen river, for example, could be catastrophic.

As I wrote, this will become a thread I’ll broaden and deepen; it weaves through a number of areas of my life/experience.