In my high school there were no + or - grades it was straight, A, B, C, D, F and the grading scale was very challenging. An "A" was 93.5% and above, a "B" was between 85.5% and 93.5%, and I don't remember what is was below that. All of the B's I got in high school would have been A- in most all other schools. 

I had friends at BYU who went to other high schools in other parts of the country whose grading scales were very liberal, with A/A- going as low as 85% which would have been a "C" for me.

My high school also did not weight GPAs for AP, Honors, Gifted or Concurrent Enrollment classes. Of the 4 Valendictorians one had retaken classes to improve from a B to an A. And two took no Honors or AP or CE classes (same with the Saluditorian). 

Similarly, my school only offered 2 AP courses and maybe 5 CE classes, contrasted to my wife's high school which offered 20 AP courses.