I have shared teaching materials with colleagues before, but I realized recently that I had seldom explained to someone else how I teach, and yet I had to do just that because someone new to teaching will be teaching a course that I have taught for a long time. I gave this person all my teaching materials -- syllabus, image files, review information, quizzes/tests, labs etc. -- but when we looked at some of it together, I realized how lifeless these teaching materials are when they are completely disconnected from the classroom experience.
For example, I can look at a list of topics and remember my explanations and examples and the questions I asked the students and what their responses were and how we discussed these, and what happened next, and so on. That's the invisible, magic part that you can't see just from looking at lists of topics or even some figures.
I don't mean magic as in pulling bunnies out of hats, although perhaps there is a bit of that sometimes (particularly in large intro science classes), but more in the sense of something that isn't very scientific, even if you are teaching Science. It's the feeling you get when you are teaching -- the energy, the interaction, the information you get from how the students respond (mostly non-verbally) to what you are saying.
The way I learned to teach was by going to the class of an extremely effective professor for whom I was a TA. I had had excellent professors as an undergraduate, but I was learning other things from them. In grad school, I was a TA and I needed to learn to teach, so I went to watch this person -- a legendary teacher -- teach a big intro science class. I went to every class, and I even sat in on the same class with the same professor for more than one term.
Some things did not translate from his teaching style to mine. He was (and is) a charismatic man. I am a profoundly uncharismatic woman. Somewhere in the FSP archives is an anecdote about how he successfully used a particular method to quiet the multitudes in the giant lecture hall. Years later, when I was teaching the same class as an instructor (just after getting my PhD) in the same lecture hall, students complained that I was treating them like children when I tried to get the class to quiet down; I reminded them of a kindergarten teacher.
The other professor had never gotten this comment, ever. Same method, different people: effective for him, not effective for me.
But a lot of his methods did translate well, and for many years I emulated his teaching style until I felt more confident and started developing my own style.
More than 20 years later, my teaching mentor is still my teaching mentor, and has been visiting me recently to talk about.. teaching, pedagogy, and sports. Or, at least, two out of those three.