A bad teacher has information to share.
A good teacher has a point to make.
I went through a lot of religious Tanach classes in my time at school. None of it interested me at all. Many positions were recited, none of which I remember at all. But then I went to a secular school, and the secular Tanach teacher had a position on everything. He would take a passage, and argue that it was imperfect, or that it was valid for the specific time in which it was written. He would back these positions up with comparisons to other religions and with logic and with literary analyses, none of which was strictly part of the curriculum. And all of this was because he was certain in his belief and wanted to convince us that he was right. I agreed with him on some points and disagreed with him on others. But I always was engaged by the argument. That was the first time I really title="The Seven Levels of Experience" style="font-style:italic;">experienced any Torah, because I wasn't just perceiving it but also using it to form opinions. I learned more Torah in each class that teacher gave than in each year of religious schools.
I wasn't interested in math going into the school system, and I wasn't interested when I left. Math was a series of rules that you needed to memorize. Toward the end of elementary school, I got a video from "The Teaching Company", of an enthusiastic math teacher explaining all of basic math. To him, math was totally obvious. He convinced me that math was totally obvious by explaining and arguing and engaging. For a few years, I was coasting on the perspective I got from that one video. All math was easy to me, because it just made sense. And then I got into more advanced subjects, and was being taught those subjects by teachers with no points to make. Math no longer made sense, so I stopped caring. I didn't really learn anything new after that. That's why I never took the math Bagrut.
If a teacher doesn't care about what he's teaching, his students certainly won't. A class is not a piece of curriculum. It is an opportunity to convince and debate. And people who don't see that opportunity should never be allowed to teach.