When it became "education" rather than teaching. So let me explain. I taught 4th grade. Math is heavy on fractions. So, to my thinking, two things in life you do using fractions are cooking and woodworking. This lead me to creating units where we learned to cook and build things with hand tools. We're making cookies. We need to know how much half a cup is, or a third of a tablespoon. Now, this recipe is to make a dozen, but we want two dozen. Anyway, you get the idea. I did this for years. I loved teaching, the kids loved learning (mostly), and my students did well on the states tests (which I hated even back then). Then things changed. Testing was king, but then it became god. In response my district required all teachers at a grade level to teach the same topics, the same way, on the same day. No more cookies. Now I had to use worksheets and constant testing. It was to the point where we told exactly what to say. It was scripted. I argued, loudly. I fought against it, but lost. So, I did it their way. My students hated math and school. There was no joy in it for anyone anymore. Then, I was told I was "under review" because my test scores were too low. I was at risk of being fired for incompetence. So, I decided to go back to doing things my own way. To fight the system. And then they came to me and informed me that at the next board meeting I was going to be fired for incompetence and insubordination. Lawyers got involved. I wound up resigning.
Do I miss it? Sometimes, but I get my teaching fix through hunter education courses and being a guest in classrooms (in a different district) for things like hatching chicken eggs or history presentations. Besides. I'm making the same money with less work selling real estate.