Here's some ideas for you:
Atutor - "ATutor is an Open Source Web-based Learning Content Management System (LCMS/LMS)" - This one is promoted as accessible, which is something you should consider when evaluating any online learning environment.
"
Moodle is a Course Management System (CMS), also known as a Learning Management System (LMS) or a Virtual Learning Environment (VLE). It is a Free web application that educators can use to create effective online learning sites."
Which Open Source LMS is best? Moodle or ATutor? - "but finally I decided to stick with ATutor"