I am looking for homework communities, online places where small groups of students of a certain category can exchange ideas about math homework. This is aimed at introductory freshman courses. One of the obstacles is the way students enter math into their answers on a web site. One possibility is using TeX, and hence equation editors come into play. There are many out there and I was wondering if anyone has used them for such a purpose, and how would you rate them. I am looking for one that allows the teacher choose the relevant buttons to reduce the clutter.
And while on the question what web site would support and allow such an activity, in a manner similar to Stack Exchange, with easy support for graphing equations. (I am aware that this is more of an education community question straddling math and TeX.)
To restate: I am after a sub-account on a site somewhat similar to Math.StackExchange.com where a teacher chooses/creates a small set of buttons making it possible for his/her students to click their way to a math formula. The students will use this for communicating with each other over their homework while the teacher plays a moderator. It is important for the palette of buttons to be customizable so as to make the approach appropriate for introductory courses. So in a trigonometry class
\cos could be a button. Some support for creating simple graphs will help a great deal.
Here is a somewhat related question on collaborative documents.
The math on Piazza does not line up with surrounding text, somewhat like math content on old web sites.