Heres my situation. My school uses the class average & standard deviation (SD) to determine grades. Grades are given out according to how many SDs away from the mean. For most of the individual subject areas, I am usually near or within 1 SD of the average. Most of the SDs are usually 2 digits (like 10 or 11), but the overall average has a 1 digit SD (like 8,9 or 6). How can double digit SDs average out to a single digit SD? (even with weighted subjects) My overall grade has been borderline twice (we have 3 units for the entire year). Im talking 1 percentage point borderline both times. I have a feeling the school is changing the overall SD, so that passing is always 70%. When maybe passing should be 68 or 67%. I dont have a problem with passing being 70%. That sounds entirely fair to me. But, that is not what they told the class. They told the class that 1 SD away is the highest grade, more than 1 SD away is another & 2 or more SD away is another. Isnt changing the SD when the class numbers dont meet their expectations (which the class was never told) the same as altering lab data for an experiment? I was expecting politics in medicine, but not starting the first year & definitely not something as major as possibly altering data. Please let me know your thoughts.