Three stars does not mean average. Three stars means it was really good. Four stars means it was excellent. Five stars means it was one of the best ever. One star is average.

You need to leave room to discriminate at the upper levels. If the book was bad, no one needs to know whether it was quite bad or really, really bad because they are not going to read it anyway. Bad book? No stars! But there’s a difference between an excellent book and best book ever! and people need to know about that.

In most American schools, you need 70% to pass and 90% to get an A. But they can’t have everyone failing so they make the exams really easy. But then all the smart kids get 100% so they have to get super-picky about trivial stuff to bring them down a couple of notches. If everyone is getting over 90% in the exams, there’s very little room for improvement. As a result of the American marking scheme, teachers get a range of about 5% to discriminate between the good students and the really good students.

When you tell an American that you got 47% in O level history, they go all sad-faced. “I’m sorry, that sucks.” But you are like, “No, no! 45% is a pass! I got a C.” Now the American is offended. “That’s ridiculous! You only knew half the stuff and they still gave you a C!” Then you explain that 70% is an A and their head just about explodes in indignation.

The further you get from maths and physics, the harder it is to get 100% (I got 100% in my maths mock O level). No one gets 100% in English Lit. Except… this one time…

Mr Anderson came running into our English Lit class waving a paper. “Alison got 25 out of 25 in her Shakespeare essay! It’s a perfect essay! In ten years of teaching, I have never seen a perfect essay before.”

At most Engish universities, 70% will get you a first-class degree or a distinction. American students coming to English universities are often a little bit shocked and assume that English classes must be easier. Nope. It’s the opposite of that.

Unlike most brick universities, the Open University requires 85% for a distinction. I hear a lot of students making the case that it’s just a different scale — like Fahrenheit vs Celsius — and an 85% at the OU is just like a 70% at other universities. I think this is wrong. When there is a narrow range for differentiation at the top, it sends a message that the grading scheme has a narrow range of expectations and if you step outside that range you’ll be penalised. It says don’t try to be creative with this or you won’t get that distinction. No colouring outside the lines.

The grading system needs to be able to say your essay was really good. You got an A. But here’s how you can do better.

Unless you got 100%.