If a course you want or need for Spring semester is full, the first step is to check if it has a wait list. Search for the class you are trying to add and check the status. If it lists waitlist as the status, you will need to add yourself to the waitlist. See step 6 in this class enrollment field guide for details about adding yourself to a wait list in UAccess: https://arizona.app.box.com/s/fwuo6w4zcu9b6at7bepk41wdpi6oluyf
For Math/Data Classes, we do not maintain official wait lists. However, the Math Center does try to help our majors who are in need of seats in these courses, so please email us at mathcenter@math.arizona.edu and we can try to help. You should still continue to monitor the class in case a seat opens and you can enroll.
If the course does not have a wait list, add it to your shopping cart so you can check on it easily. Check on a regular basis in case seats open up. Over the break, students make many changes to their schedules and seats may free up during this time. If the course has pre-requisites, seats will open up after students who failed to complete the pre-requisite are dropped.
You may try contacting the department that offers the class to see about possible enrollment, in case their administrators are responding over the winter break.
In some cases, you might be able to talk to the professor on or before the first day of class to ask if there is room for you to join the class, but this is not always the case. Check with the offering department to see how enrollment requests are managed.
We do NOT recommend attending class on the first day if you are not officially enrolled, since the classroom may not have sufficient physical space/seats to accommodate extra students.
If the class you want can be replaced with another class that is open (ie. a different general education class) please add your second choice class, but watch for a chance to swap it.