I am working on plugging WeBWorK in as a back end for analyzing mathematics questions in a way similar to STACK. I will be using the opaque question type as a starting place.
I am just beginning this project and I expect to have questions for this forum as I proceed so I thought it a good idea to introduce myself.
I am Mike Gage, a math professor at the University of Rochester, (Rochester, NY, USA) and one the originators of the open source online homework system WeBWorK. It was originally designed to deal with mathematics at the calculus level but it now has questions from middle school through ordinary differential equations, linear algebra and complex analysis.
It already interoperates with Moodle as an assignment module -- there is single sign-on between Moodle and WeBWorK and after the student finishes their WeBWorK homework assignment the grades are returned to the google grade book. My goal is to make WeBWorK work as a question type for Moodle2.x. We already have a version question type version for Moodle1.9
For those interested here is an example of a course using WeBWorK for assignments (search for the spiderweb icon and click on it). https://hosted2.webwork.rochester.edu/moodle/course/view.php?id=3
For those interested in an example of WeBWorK being used to create question types in Moodle 1.9 (Created by Matt Leventi in 2007) https://devel1.webwork.rochester.edu/moodle/mod/quiz/attempt.php?q=256&forcenew=1
(you can log in using the guest button). This version could use improvement but I don't plan to work on this further unless there is a large demand -- it seems better to put the effort into a Moodle2.x version.
Finally for those interested in WeBWorK in its native form you can look at this link:
https://hosted2.webwork.rochester.edu/webwork2/2014_07_UR_demo/ (you can login using the guest button)
The home wiki for WeBWorK is http://webwork.maa.org/wiki
Thank you in advance for considering the questions I will have as I start on adapting
the opaque question type to WeBWorK.