a wide variety of scales used in books and other schools.<<<<
I used this grading scale:
I chose it because I wanted my kids to work for mastery, but not necessarily perfection. If they demonstrated mastery, with 90% or more, then I gave them an A and a 4.0.
I also chose that scale because it made the math on the transcript easier.
I don’t think it matter WHICH grading scale, I think it just matters that you have one for the purposes of your transcript. Just choose a grading scale – ANY grading scale. If you simply can’t decide, then throw a dart at it!
When my children started college, I saw the different teachers all choose different grading scales for each class. The college itself chooses another grading scale. There is a huge variety out there! Just do what’s right for your child.