DS1 is not that academic. At school he's always muddled along somewhere round the middle. He shows the odd burst of enthusiasm but it never seems to last long
I have been trying to push him to work more, revise, or even just TALK to me about how he was getting on. His marks are as they always have been ...OKish but not good. But he assured me he's doing fine, he's not worried.
First science modules I helped him to revise as he was a bit worried and he got Cs for all three subjects - about par for the course unfortunately.
But last night I finally managed to have a coherent chat with him. He's really worried about his marks. He is only doing foundation stage maths and both modules are after half-term. Even that is a disappointment as in primary the head described him as a 'natural mathematician'. Currently he isn't sure he's even going to pass that
I will do anything I can to help but FFS why couldn't he tell me earlier that there were problems? Tutor hasn't really helped - just tells us there's nothnig to really worry about.
I've ordered a maths GCSE revision book from Amazon and I guess that's what we'll be doing over the half term. Joy! 
Any more ideas? Please? I am feeling utterly despondent.