This particular missive - forwarded, not composed by Fearless Leader - has a section about why we shouldn't use zeros when we grade.
2. Zeroes involve inappropriate mathematics
Most state standards in mathematics require that fourth grade students understand the principles of ratios - for example: A is to B as 4 is to 3; D is to F and 1 is to 0 (sic).
Yet the persistence of zero on the 100 point scale indicates that many people have not applied the ratio standard to their own professional practice.
I wish I could show you the entire PDF but unfortunately it's too long to post here. Let's just say that it reminds me of what I used to see from third graders when they learned how to do effects with fonts and use clip art. A little knowledge of Microsoft Word is a dangerous thing.
Anyway, I suppose this person is trying to say that you can't divide by zero? Well that's true. However, what the author of this generally nonsensical document fails to realize is that the introduction of zero was seminal in the advancement of mathematics, and without it modern math would not exist. Also, grades aren't ratios!! The only division that takes place in a numerical grading system is when you take averages, which can never involve division by zero. In fact, when doing numerical grades, a zero generally indicates exactly what it's meant to, conceptually - nothing. A zero on an assignment means it was not completed.
Now why am I posting this? As you know if you read this blog regularly, I don't think students should be graded at all. I'm just pointing this out as another example of the idiocy that is endemic in "educational" institutions - at least public K-12 ones. This is a document that our principal thought fit to forward to the entire staff to help us as we're doing grades, and it looks like it was written by somebody with less education than we're supposed to provide to our students. This, unfortunately, is par for the course for things teachers are given for our "development." It's either nonsense, pure jargon, or both.
Please, please, please get your children out of public school.