Is it appropriate for a student to attend a class s/he is not registered for?
I am a CS student and I am almost done with my degree, but there are some very interesting electives that I will not get to take and I would love to simply attend those courses any way.
Is this inappropriate to do? Should I ask the professor's permission first?
I am not sure what my school's policy on the matter is, since I could not find a single source on the topic online from them.
In the American system, this is called "auditing" a course. Auditing means that you are attending the class but are technically only listening (auditing => auditory => listening) to the material and not sitting for exams or handing in homework assignments. You can audit a course formally (which often means that this is listed on your transcript) or informally in which you just sit in on the lectures/discussions. For the former/formal, see your local university guidelines. This answer deals with the latter.
Permission of the instructor in all but the larger lectures is always a good idea unless your university has an open classroom policy (as with many European universities). The instructor may have different rules. For example:
Note that the university itself may have rules on auditing which the faculty member may ignore (for example, I do not mind if local community residents audit my lectures even if they are not registered as auditors through the university).
This is different from PASS/FAIL (also known as CREDIT/D/FAIL) which is another alternative in which you take the class but are allowed a lower level of participation.
Should I ask the professor's permission first?
Yes, this is the polite thing to do. (It's a perfectly reasonable and common request, so no need to be embarrassed about asking.)
As an instructor, it's useful to be able to understand any apparent discrepancy between the number of "official" students and the number of students I see in class. (For example, for determining whether I need to reserve a bigger classroom for an exam, or if I need extra TA support.) So even though I've never turned down a request like this (given that it's permitted in my university), I still like to be asked.
Some schools have an official policy about this kind of thing. If you couldn't find anything relevant, maybe the professor will know and will clue you in when you ask him.
Other, more qualified, people have answered your direct question, so I will add to it without detracting from what they have to say.
There are some schools with 'alumni audit' policies, in which - as the name suggests - alumni can formally audit courses. Check with the registrar on policies about this. If your school has such an option, find out the rules. Some classes may be auditable and others may not. Some may be auditable online if you are far away from your university...etc.
While you will likely only be able to do this for one course at a time for courses offered at night, assuming you work a day job, it could be a good way to take those elective courses, create & maintain relationships with professors and with your university.
Good luck with your studies, and have fun.
I'd like to add a perspective from Germany:
Fees here are usually paid for the fact that you are registered as a student (typically a general service fee, student union fee, possibly obligatory bus ticket), only very particular courses have course fees (sports, languages, and postgraduate courses that get you certified for sth. come to my ming). And even if you do your PhD without being registered as student or work as post-doc, for general lectures usually nobody checks whether you are technically "allowed" to attend the lecture: many lectures are anyways public. Registration is required if you want to take an exam and get a certificate, but usually not if you are just interested in the knowledge.
So for most lectures it would be totally OK to just attend and listen. That is, unless it is really crowded: then it would be seen as impolite to take away the seat of a student who needs to hear that lecture. So for certain subjects, you'd just not get in in a polite way, whereas in others (SMT) the lecturer may be happy to have one more face in the audience.
In fact, a certain amount of broadening your horizon is encouraged ("studium generale"). For that purpose, lectures that are of interest to students of unrelated subjects or the general public are often offered in the evening hours. For example, I heard some more physics than I was required, plus a bit of philosophy, computer science, economics and law and got an introduction to Polish language (I'm chemist).
For language and sports courses you'd typically be required to register. And you may not be that welcome to more intense courses that are meant for smaller groups such as excercises and lab practica (where there would be questions as to who pays insurance and material as well as safety concerns such as whether you know what you are doing).
As a student who has attended four universities and counting, I can provide a student's perspective on this subject.
Most large state schools require auditing students to pay the same tuition to audit a course as it would cost to actually take that course for a grade. The ethics of this are debatable, but I personally disagree with it strongly.
If your university charges to audit a course, then I would consider asking the professor if you are aloud to sit in on some lectures. The professor may be alright with you 'unofficially ' auditing. However, this will depend entirely on the professor and how strict your university policies are.
If the course is very large, as many entry level courses are in state schools, then you can consider just auditing unofficially and without permission. Be careful though, you would potentially be violating university rules, and may anger the instructor. But, if it's a large class with hundreds of students, chances are you will not be noticed, and your presence will not detract from the course. Learning is never a bad thing, and charging students to audit a large course like this is wrong, in my opinion.
Keep in mind that when unofficially auditing a course, you will most likely not have access to any online material used, and be unable to submit assignments/take exams, unless the instructor agrees to allow otherwise.
Overall, never stop learning. If you want to learn something then it's up to you to seek out that knowledge whatever way possible. No one will fault you for this morally, but Universities don't like missing out on tuition fees. Don't get in trouble.
Policies vary, from university to university, and even from department to department in the same university.
The first thing you MUST do is to ask the professor for permission. Not doing so, is a form of "stealing." If you have the professor's permission, it's more like borrowing.
The professor will usually know what the university's policies are, or at least be in a position to find out. In some cases, there may be an extra fee involved, for as many credits as the course is worth.
In some cases, there may be "loopholes," that is, there is no problem if you audit for less than half the semester, then "drop out." Some universities will allow you "sit" for three to five lectures early in the semester before having to choose between courses. In other cases, you may be allowed to attend ONE lecture on a particular topic. (I have used all these strategies in my career).
In any event, do what the professor tells you. That is the best guide for "university" policy, as well as his/her own.
