School has started and it is now the add-drop period! The add/drop period lasts for 2 weeks. During this time, you can attend all the classes you want (provided your schedule allows for it), to see whether you are interested in adding/dropping the course.
Enrolling via authorisation code
If you do not manage to enroll before the semester starts, which is a rather common situation, you can still enroll after getting what is known as an ‘authorisation code’ from the professor.
How authorisation codes are assigned
If there are insufficient codes for everyone who wants to enroll (but didn’t manage to), then the professor will either prioritise based on whether you’re a phD student, an exchange/international student and/or other reasons, such as the course being a compulsory mod for your major.
Also, this point has been mentioned in a 2018 NTU post I believe, but no harm mentioning it again! It would be good to sit at the front of the class if you are trying to get the authorisation codes, as queues normally start from the front/sometimes the slips are being passed from the front.
Check your mini-course dates
Another point to note is that if you sign up for a mini-course, do check whether the dates make sense! The mini-courses can be registered at the same time as your semester courses, and the course description do not write the dates beforehand. When I got here, I realised the description was updated (with no email announcement on it) with dates in August.
After emailing the professor, I realised that while the mini-courses were open for registration at the same time as the other courses, they are actually being held before the semester began! Good thing this was asked during the add/drop period, or it would have required more emails to remove the course from our list of registered courses afterwards.
The last thing I want to note about adding/dropping of courses is actually something I find rather important! If you didn’t manage to get the course or code and the module is something you would very much like to take, do email the professor to see if there are somehow some available slots left. If there aren’t, at least they know that there is a very keen student who is waiting for a slot and you might be notified of the slot first if anyone decides to drop the course. Of course, do remain understanding and polite regardless of the situation.