It's simple, really. In order:
- Motivation. A teacher must create motivation in the students as their first and primary job. The cheapest way of doing this is by having a large personality that gets students excited about learning. Every movie on good teaching centers on this point, but no one talks about it. Teaching is primarily about motivation. Secondarily, it's about anything else. ASIDE: Almost all of the very best teachers I've seen have been sports coaches first. Motivation wins...and sports coaching helps to teach motivation. OTOH, many teacher-coaches (in my experience) don't care about the topic they're teaching, and don't exert the same coaching skills to motivate their econ students as their football players.
- Practice. A teacher must give students a chance to DO. Teacher talk is not worth the paper it's printed on. At this point, I'm wondering if I could teach high school math for a year without speaking. Practice is hard. My experience, both in the schools and in the corporate education world, is that practice is really poorly designed. If I were God, teachers certificates would be 70% about designing effective practice. The thing that Montessori, and then later Englemann did that is so cool is that they designed effective practice.
- Feedback. A teacher is responsible for not only allowing students to do, but also ensuring that as the students do, they get feedback about how they're doing. American schools used to be merely bad at this, now they're atrocious. Feedback has several dimensions, but topical and timely are the top 2. You missed 3/20 problems is not as good as This problem that you just did is not as good. Assessment is a form of feedback.
- Adjustment. If you're a teacher, your lesson plan is wrong for most of the students. Too much time, too little time, too many topics, too few, too many examples, too few...etc. Teaching requires constant adjustment to the actual needs of the students in the classroom. Anyone following a plan instead of adjusting to the reality on the ground is either having a lucky day, or not teaching most of the folks.
- Clearing Confusions. Sometimes, students practicing find that something does not make sense. This sometimes requires teacher assistance. The most complete assistance is guided discovery, but that's sometimes not efficient. #2 reason, in my experience, that people stop learning in a direction is that it's "too hard". Really, that usually means that they hit a snag, and no one helped them through it.
- Other Issues. Teacher is an authority figure. This means they get to deal with all sorts of crap that has NOTHING to do with education at all. General competence as a human being, and a caring one (many issues are social/emotional) is important here.
- Instruction. (aka Explanation) This is what everyone thinks teaching is about, but mostly it's a side issue. The person who figures out how to capitalize on this feature of education wins. This is why Khan Academy is profitable, interesting, well taught, and mostly useless. When you know stuff that you just "learned" from the discovery channel an hour after the show closes, we'll talk. It's placebo against the fact that learning is about DOING, and sometimes about practice, and only septenarily about instruction.