I'm a teacher who is doing some research on how grading system cut-off
scores are determined. For example, how did 3.6 - 4.0 become an A and
3.0 - 3.5 become a B grade...equally, who or how was it determined
that 90% constituted an A on a 100 point scale. I'm having a hard time
finding out the answer to this question and it seems rather arbitrary
in the manner that the whole A,B,C,D,and F grades are assigned
percentages...0-59 = F, 60-69 = D, and so on. I'm trying to understand
the method by which these terms, or grading scales came to be and how
they were determined...was there a formula, was it just someone's
idea, etc.

Please e-mail me if you have further questions or need clarification.
Time is of the essence.

Best regards,
Alex

blyx...

I haven't done so well at finding the origins of systems
you've asked about, but I've found a fellow teacher who
speaks with authority on how the system is designed to 
work so as to provide fair grading. I would imagine that
the author of the system(s) provided a similar rationale,
so perhaps you will find this useful.

The article is by Scott Mandel, Ph.D., on EducationOasis.com:
http://www.educationoasis.com/resources/Articles/beginners_guide_grades.htm

sublime1-ga