One of the perks of this job, at this school, is I get to teach a lot of different classes. I get to think about concepts, mathematics, and experimental work every semester. If you count the lines, there are 15 of them. But, the lab courses for Phys 111/112 and Phys 211/212 are separate lines in our catalog. So, I guess that means I've taught 19 different courses since 2009 (the year I started here). Omitting the Special/Selected Topics courses (I've taught the Phys 190 course once and developed a Phys 490 course that didn't reach the enrollment minimum) and Senior Research (I typically mentor 1-3 students per year in this course), students have a choice of 26 courses. (I'm also omitting Phys 106 because it is never offered in this way. It always shows up as Phys 106A, 106B, or 106C.)
What this all means is I've taught a little over 70% of the "subjects" offered by the Physics Department at SVSU. I don't know how that compares to a national average among Physics faculty, nor do I know how it compares to other disciplines. I kind of feel like it's a lot, though. The most beneficial part of the diversity of teaching is I have to think about some idea at a very conceptual level in one class, then present it in a fairly rigorous mathematical way in another. One semester I was teaching Our Physical World (terminal 100-level course for non-majors general education credit) and Solid State Physics (optional 400-level lecture taken by graduating Physics majors and minors) with a 30 minute break between them. It was pretty fun.
I approach teaching starting with the idea that I cannot make anyone understand anything. They must create their own understanding. My job in the classroom is to help students feel comfortable not knowing the answers. Many of the things we discuss in Physics are "common sense." That is, until you start to think about them. Then you recognize your common sense is rooted in personal experience. Generally we don't have a broad base of personal experience when it comes to physical phenomena. If a student does, they generally haven't had the luxury of picking at their internalized explanation of the phenomena. This is not something most people like doing because it will (eventually) lead to a contradiction or (more likely, and) a recognition that our entire world view is built out of dried sand. It is disheartening when that crumbles.
But crumble it must if we are to experience intellectual growth. I strive to create a space where each person may confront their confusion in an honest way, unburdened by judgement - either from the self or from the other. This is why the first course expectation in every syllabus I write is "Each member of this course will treat all members of this course with respect." The moment of recognition that we don't understand what we mean when we say something is the moment I chase.