The phrase "to get good grades" means to achieve high marks or perform well in academic subjects, typically as measured by a grading system. Full definition
The quality of dissertation is very crucial as per the point of view for getting good grades in the dissertation assignments. (studentsassignmenthelp.com)
If your child comes complaining to you that mom said he can't have TV because he didn't get a good grade on your last test, don't undermine the other parent! (huffingtonpost.ca)
You are not high school any more, you will get a good grade for writing at least something and meeting a word limit. (customcollegeessays.com)