Grad students must have an average of 80% and at least 72% in each course for it to count for their breadth requirements (see http://www/grads/affairs/Handbook.pdf)
If you want to give a student an extension at the end of the term, in FSC, you can enter a "T" for Thesis in Progress or you can just leave it blank. If you enter "T", then you would need to submit the change of grade form when the student completes the course requirement. Some instructors prefer leaving it blank to avoid the paperwork. There is no published deadline for filling it out, and other students should be able to see their grades as long as you "submit" (not "save") the grades.
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TAs
Joyce Poon and the "TA coordinator" elected by CSGSA (see http://www.cs.ubc.ca/spider/csgsa/representatives.html#Other) will select your TAs for you. If you want TAs with particular backgrounds (e.g., classes on transcripts for the first years) and you don't think they'll be familiar with your needs, contact Joyce or the coordinator early!