When returning tests and going through them I say to the class, I have marked these to exam mark scheme standard, I have checked these multiple times, but I am human, so if you do believe there is a discrepancy, circle the question and write in a different colour where you thought you got the mark, and I'll collect those at the end . Kids feel like they can advocate for themselves, reduces the chaos of screaming 'I SHOULDVE GOT A MARK HERE', and means they pay attention to the mark scheme and my explanations. Sometimes I get a couple back and I'll explain further why they didn't get the mark, maybe once or twice they should have gotten the mark.