After the umpteenth conversation with Ds about why he's dragging his feet about revising, I think I finally got to the bottom of it this morning:
naivety.
He's at a comprehensive and that means all abilities and all attitudes to the value of education and the point of qualifications. He's in the top set for everything and I thought that meant he more or less adopted the attitudes and habits of the rest of the top set. But no, apparently not. He says the top set are now immersed in revising, and some of the second sets, but otherwise year 11 students are resisting doing any work.
As an example, one of his subjects has low uptake, so the class has more mixed attainment levels and DS sits in a row of 4 boys. Every time the teacher says that they should be doing x,y or z in their own time to prepare for the exams, the 3 boys next to DS all start swearing at the teacher and refusing to consider it.
So, DS thinks that he's doing more than most and I'm unreasonable to suggest what he's doing is inadequate.
Technically, he's right: he is doing more than "most", its just that "most" includes a lot of people with low ambitions.
TBH I feel sorry for the teacher. You can bet that next month, those boys who've been ignoring the teacher's pleas that they pay attention since September 2016, will expect the teacher to give up their free time in March/ April and May and by April, when they learn that they are on course for low grades, they'll be loudly proclaiming that its the teacher's fault and that the teacher is "fing sht".