What does it mean to 'crash' a course?
Crashing a course, and it may go by different names at different schools, is the process of doing a sit in and trying to get into the course, even though it shows that it is full. If a student goes to registration, for example, and finds that the class is full but that student needs that course for graduation requirements and it is maybe next year that they're going to graduate, and they need that prerequisite this year and that course is always full because it's popular, many times students will crash a course. This involves going to the class at the day and time that it meets on the first day and sitting in the class, even though it's probably going to be full, and waiting for the instructor to recognize or perhaps even going to them in the beginning of class and saying "Are you accepting new students?" This is when the instructor will tell you how they feel about this process. Many times faculty members don't appreciate this, because it says that you are perhaps not following the procedure process. It's also difficult because those seats in that classroom are a limited resource. Many times faculty members will consider the fact that there aren't that many classes required and that their class is very important for graduation, and they will say, "Okay, I'm willing to let only graduating seniors into my class at this time", or "If a few of you are considering dropping out, this is what my class is going to entail." Then people may leave who are already registered. The bottom line is that it benefits you to ask. It doesn't hurt to ask whether or not you can add that class even though that class is full, but you need it for graduation. By the same token, if you don't need that class for sure this semester, it may be better to spend your time elsewhere.