Math education! r/matheducation is focused on mathematics pedagogy (the teaching of). Please avoid posts that are related to homework or other "How do I solve this?" type questions. There should be an emphasis on usefulness (such as good internet resources or ideas for how to teach a concept).
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.
A subreddit to draw simple physics questions away from /r/physics. No real rules; ask away. If your basic physics question isn't answered in a day, you can post it to /r/physics if you mention that you didn't get an answer on /r/AskPhysics (unless it's a homework-related physics question).