My courses are graded on a 4 point scale, similar to a GPA.  Even though the university does not give +/- grades in their classes, I do use them in determining my grades.  I do make mistakes during grading, so if you think you deserve more points on a particular questions, PLEASE come ask.  I may not agree, but I want you to understand why points were taken off.  The specific grades awarded are:

A+    4.3
A      4.0
A-     3.7
B+    3.3
B      3.0
B-     2.7
C+    2.3
C      2.0
C-     1.7
D+    1.3
D      1.0
D-     0.7
F        0

Each grade item (exam, lab, etc) has a percentage of the total grade associated with it; i.e. 15% for a lab grade.  Multiply each grade by the corresponding percentage, add up all 100% of the class grade, and that gives the individual grade for the course.  For example, if a student earned an A- in the lab worth 15% of the course,  B-, B+, and A on three exams each worth 16%,  a B on quizzes worth a total of 15%, and a C on the final exam worth 22%, their total grade would be:

A-   3.7 * 15%  =  0.555
B-   2.7 * 16%  =  0.432
B+  3.3 * 16%  =  0.528
A    4.0 * 16%  =  0.640
B     3.0 * 15%  =  0.450
C     2.0 * 22%  =  0.440
               100% =  3.045  which corresponds to a solid B for the class.

While I would like to be able to give each student a good idea of their grade at every point in the semester, much of your total grade is determined at the very end of the semester.  I return each exam with a point score, which corresponds to a letter grade as shown on the grade distribution for that exam, and I am more than happy to discuss your quiz grade with you throughout the semester.  Lab grades I do not receive until the very end of the semester, so please discuss those with your lab instructor.