Eli5: In American schools, the letter grading scheme is: A,B,C,D and F. Why did it skip the letter E?

Question

I was wondering why the letter grading scheme is like this. Why did it skip the letter E?

In: Other

Answer 1

In my country we have letter grades for the first cycle of school (FB – Very Good, B – Good, S – satisfactory, I – not satisfactory).

Then for the next cycle we have a number system from 1 to 10. This system is also used next in highschool.