At a different conference for science teachers, Lauren was talking with another science teacher who also taught physics, but at a public school. Now, there's one main difference between public school teachers and private school teachers: they are certified to teach, which means they have degrees in education, while we are not and typically just have degrees in our subject area. Lauren, for instance, has her degree in Physics (though she has also taught chemistry and, at one point, anatomy/physiology as well); the man she was talking to had a degree in science education, and with that he had taken just a couple classes in physics, which basically meant that he's one step ahead of his students. In other words, he knows a little bit of each science, whereas Lauren knows one area of science very well (though I should add that she's very well-prepared for chemistry and anatomy/physiology as well, as she was on a pre-med track). I think this tendency is most pronounced in areas like the sciences or "social studies" (in the private schools, teachers tend to be history majors) which cover a wide range of sins. In English, for instance, I suspect that the difference is much less pronounced, and in music, teachers are probably better prepared by an education major than a simple music major.
I suspect that education degrees could be very useful things, but the majority of public school teachers I've spoken with have not found them to be so. To that extent, it may be that such courses take away time that could be spent improving one's knowledge of one's subject area. Yet it seems that prospective teachers in education programs at least could be learning important things about teaching. We private school teachers have a tendency to model our teaching on teachers we've admired, which often tend to be our college professors rather than our high school teachers, which inclines us to practices more like college than high school. This can be tough for our students, as we've thereby set high standards and may not be aware enough of the need to "scaffold" for our students, but at the same time it can cause us to set higher standards that more closely approximate college and thereby prepare our students well for their later studies.
We also, for better or worse, learn from our colleagues. We also attend professional development opportunities, such as the conference I'm at now or graduate school. One way or another, those of us who stick with the profession learn how to teach at least as well as our public school counterparts. Nonetheless, we can't teach in public schools, no matter how much experience we have or how good we become at teaching, even if we have a better mastery of our subjects, unless we go through the rigamarole needed to get a teaching certificate. It seems strange to me.