No 'E' for Effort?

Here's something interesting... I saw an article on Yahoo's front page yesterday that some high school somewhere was trying to get rid of the 'F' on the grading scale. I didn't really care about this and I did not read the article - that's not really what this post is about. Here's what I want to know... Why has there never been an 'E' on the grading scale?

Obviously the scale is alphabetic and has nothing to do with acronyms or abbreviations.... basically, it is just a letter grade assigned to a range of percentage points, I suppose for clearer presentation and to allow for some "wiggle room" within the range (i.e. 90-100% = A, 80-90% = B, etc.). It's quite obvious to start at the top with an A, and then follow in succession with the B,C,D. I guess I get that an F can stand for Fail, or Flunk, but why not an 'E'? Is there too much latitude with a 6-letter system? Does 'F' just have that much more punch over 'E'? Maybe it seems that way since we're used to hearing "eff" in that hard tone and it carrying such a negative connotation... Is E a happier letter than F, tonally?

Either way I feel bad for the 'E' getting left out like that. I think when I have kids and they are in school, I will find a way to squeeze it in when they get report cards. Of course since an E would be just barely better than an F, I suppose I hope I never have to have that conversation with my future kids... as I would much prefer it if they were scholarly... like their old man!

I give this post an 'A'... feel free to give it an 'E' if you disagree.