I noticed that some teachers announce the grade breakdown in the first class or in the syllabus, while some don't. What's the best practice? If giving the grade breakdown at the beginning is preferable, is it better to use an absolute or relative breakdown?
Example of grade breakdown announced in the syllabus (absolute breakdown):
Letter grades are determined at the end of the semester. The default cutoffs are: a final average of 90 and above is an A, 80 and above is a B, 70 and above is a C. These boundaries may be adjusted downwards if necessary because of the difficulty of the assignments or quizzes, but the boundaries will never be adjusted upwards, so a final average of 90 is guaranteed to be an A. The boundary adjustment is done heuristically, and there are no grade quotas, no grade targets, and no centering of the class on a particular grade boundary.
Example of grade breakdown announced during the first class (relative breakdown):
The first half get A, the second half get B (except in case of failure to try to do the homework or show up at the exams).
I am especially interested in computer science education in the US.