Just had to say - hunker, you and I had the same school experience. I did have experience of the private sector, and went to dreadful and terrific state schools (we moved a lot)
I had one teacher say to another class (same year group, same subject)
"Do any of you know Humph? It's so annoying. She sits at the back, messes around, never does any work and she managed to pass the exam. And then there's X, who sits at the front and works hard, and she didn't pass. Useless Humph."
wtf
Obv, the people I knew in the other class had pretended they didn't know me, and relayed this back to me.
So now I think, there was I, passing without doing a spot of work and the teacher was criticising me. Why didn't she move me to the front and encourage me? Because she was the useless one, the numpty.
Rant over.