Your post struck a chord with me, bluefineliner! DS is very much an absolutist about his grades, even if he doesn't need absolutely top grades to get to where he wants to go. And right now he's suffering a real crisis of confidence about not only his exams performance but the validity of his chosen degree and career, and his place in the bloody universe ...
Some of our young people can be so easily thrown down by a 'bad' practice paper (or god forbid, a 'bad' actual exam) and it's so hard to lift them up again. Your DD and my son really do know more than they believe they do, but it's so hard to convince them of that!
DS also has Chem 1 on Tuesday and his humanities subject on that same day, which I know happens but seems so unfair! 3 next week, 3 the week after and then 2 on consecutive days the third week. I'm just praying DS can get his exam head back on and turn into a bit of a machine for the next three weeks.
(sorry to gatecrash at this late stage, btw. I've been reading this thread for the last couple of weeks...)