You can join courses as a “guest student“. A guest student is a student who is not officially registered/has not yet registered for the course. A visiting student has all rights in a regular student’s course (solving exercises, participating in a forum, etc.).
You can join Moodle courses as a guest student by self-registering for the course mailing list. Registration will take effect the following day.
Make sure that the course has a website in the system by searching the list of courses available in the system. A link to the list appears at the bottom of your course list.
Attention! Registration through the mailing list allows only access to the course website and is not a substitute for official registration on the undergraduate studies website.