I find it difficult to separate the "teaching practices" from the "teaching content." Wouldn't the approach the teachers take be dictated by the textbooks they're using? Even in primary school, a good lesson would be planned around some activity or handout. Or does every teacher just improvise the lesson on the spot each year?

From what I know about teacher portfolios, their focus is often "too meta": they discuss the process the teacher used rather than share the actual result (e.g. lesson plan, notes, or slides).

At the education meetup during Pycon 2014, Greg Wilson of software-carpentry asked a really good related question: Why does open source work so well for code and not so well for educational content? I don't know if anyone has an answer to that yet... Why is OER not taking off more? Here is a blog post of my own ideas about what git-for-authors could look like: https://minireference.com/blog/git-for-authors/ It's a really interesting space to watch.