Math education! Anything math related that is useful for education, teachers, or students. There should be an emphasis on usefulness (such as good internet resources or ideas for how to teach a concept). Note: This is not a subreddit to publicize each post in your (or any single) blog or website, but rather to point out resources you've found that you could actually see bringing something useful to a math class.
The aim of /r/Physics is to build a subreddit frequented by physicists, scientists, and those with a passion for physics. Papers from physics journals (free or otherwise) are encouraged. Posts should be pertinent, meme-free, and generate a discussion about physics. Please report trolls and intentionally misleading comments.