Sparked by the discussion in the comments in the question How to teach modeling physical systems, especially if it is off-topic, I started looking for pedagogical questions about physics. I didn't find much and there is no site comparable to Mathematics Educators Stackexchange, where pedagogical concepts and methods are the main focus. What I did find was the meta post What kind of [education] questions should we allow?, which dealt with this topic partially.

The way I understand it, questions about pedagogy in physics are currently not allowed, because they tend to be too broad or opinion based. I think, that if such a question is purely about opinion, than it does not fit the format well, so it shouldn't be allowed. But there definitely are objective answers, because pedagogy is an active field of research and as one can see on Mathematics Educators, there are some general principles one can follow to improve teaching.

The reasons why I think this is important are:

1. Physics education is a topic often encountered by teaching assistants and professors on a daily basis, but (at least in my experience) there is barely any pedagogical education beforehand. So these questions would serve as a starting point for improving teaching skills.
2. There are some challenges specific to teaching physical concepts in contrast to general pedagogic techniques. My original question is about such a problem, why it does not really fit on other sites in my opinion.
3. Even if one has a general pedagogic background there might be students for who the general techniques fail. In this case it would be nice to have additional options to try, many people learn differently.
4. Science communication is an increasingly important topic and pedagogy can help with it. By learning about effective explanatory concepts, it is easier to find an explanation, that the general public can digest, but is still correct.

As a solution I see three options:

1. Keep the current policy and close pedagogy questions as off-topic. I do not prefer this because of the reasons above. In this case, future questions can be linked to this post.
2. Create a separate Stackexchange community like Mathematics educators, that primarily focuses on these topics. This would fracture the community a bit and prevent the general users to take a look at these, but keep Physics SE clean.
3. Create the "pedagogy" tag on the main site under which these questions can be discussed. This would be my preferred option, as people who don't want to see these questions can block the tag, but it is still available to general users without subscribing to an additional site.

Of course there may be other options, but these are the obvious ones to me. So my question is: what stance should we take on questions about pedagogy, specifically for concepts in physics?

Given that there are Computer Science Educators and Mathematics Educators communities and that this question (or similar) has been raised in the past, perhaps the creation of a Physics Educators / Science Educators / Physical Science Educators community is the way to go.

I agree with Mick, that a separate Science Educators website (your option #2) would be the best way forward.

It might divide the community but there are already divisions in the SE family between Physics and Engineering/Electronic Engineering, Signal Processing, Computational Science, History of Science, Astronomy, Space Exploration, Mathematics, Statistics & Data Analysis etc. Many SE members are active on more than one site, and it is very easy to switch between them.

When new sites get established this enables those who ask and those who answer to link up more efficiently. Educators get better answers more rapidly from a site which specialises in teaching and learning methods and issues, rather than a site which focuses predominantly on explaining the concepts of physics and applying them to particular situations.

What kind of [education] questions should we allow? deserves more attention than it got. @Wouter made a very good observation that even the most objective question about physics is subjective to some extent.

However, questions about teaching and learning methods and also book recommendations, which are both currently officially on topic here, are generally broad and subjective, and it is particularly difficult to identify and specify all relevant circumstances. As dmckee notes in a comment to your Physics question, the same method applied by different teachers often has different results. And even the same teacher does not succeed in applying the same method to all students. What exactly is it that accounts for the difference? From very my limited experience I think that teaching is an art not a science - you succeed by accumulating a broad range of tricks and being adaptable, not being dogmatic about which is best.

It is difficult to justify keeping such question on this site while at the same time closing other questions as too broad or primarily based on opinion - often to a lesser extent - simply because they don't qualify for the protection of the education or resource recommendations tags.