I have a degree in education and fortunately had a second major because i found during my first year of teaching that I hated it. Not the kids-they were delightful. The administration and other teachers that had no idea what they were doing really bothered me. I think the big failing of education is the lack of subject matter experts. Teachers with degrees in education who are really not qualified to teach anything except perhaps education classes. Many don't know their English, History, Geography, Math or Science. All they know is how to work the system. When my kids were in the German-American school while I was overseas they were acquiring an actual education. Secondary education in many parts of the US is terrible. I had to move my kids a couple times to find good classes. in one secondary school in Maryland I went to talk to the English teacher and found that she barely spoke English herself. i talked to the math teacher and he admitted he was a phys Ed teacher and not even a page ahead of the kids in the Algebra Class. When I talked to the Principal he literally said "What do you want me to do, I have to work with them as it is impossible to fire a teacher". And they can't hold a non-performing student back.
Ok, Rant over. but I don't think anyone should be teaching accordion who can't play one.
OK, in a program like mine, you could be called on to teach any subject at any grade level, at least that's what the New York City license 'Teacher of Homebound Children,' stated. But as a practical matter, we were divided into elementary, middle, and high school groups. In addition to that, we had, at middle and high school level, specialists in mathematics, foreign language, and, at high school, sciences. How did I get to specialize? I always had a strong interest science, particularly chemistry. The chemistry specialist in my group retired, and I got a student through a difficult exam with an almost perfect grade around the same time. Now, the curriculum had certainly changed from the time I took the subject in high school to something closer to what I experienced in college, but a new textbook that helped both teachers and students also came out around the same time. What homebound students couldn't experience, of course, was the laboratory. We were able to get that waived as a course requirement until a year or two before I retired. After that, if students were able to return to school before the academic year was cover, they could make up the lab hours. If not, they could do their labs before or after their regular classes and then take that exam a year later.
Sometimes, however, particularly near the end of a semester, a newly homebound student needed the services of one of our specialists and our schedules were full. In that case, the so-called regular home instructor would have to do it in that "one lesson ahead" fashion. I recall one of my colleagues getting a call from his supervisor:
"What language did you take in high school? [My comment -- high school, not college.]
"I took French,"
"We have a new student who's taking Russian. You're it."