In our first year math class, we deliberately took modules which had a fair bit of overlap with our A level math. We did learn new stuffs, but there was also definitely a heck of overlap. Of cos in uni math, you have to know and use stuffs that you learnt in pri, sec, and JC. I'm not saying they still teach you how to add 1+1. But when I said "overlap" I really mean stuffs that they taught from scratch as if you had not learnt it at all earlier.
Needless to say, most common undergrads like us wanted the best results with the least effort. I got A+ for some of them. At that time, it felt shiok, but now when I look back, it doesn't mean much as far as learning is concerned. Anyway, I've thrown back almost all of the stuffs I theories and formulas I knew so well back then.
And another thing I'd like to add regarding why those who go overseas can get good grades despite not doing well here. It's not always that overeas unis have poor standards. But rather, those fortunate ones whose parents are rich enough to sponsor their kids for an overseas education choose something they are interested to study. Over here, people just wanna get into uni. Unfortunately, many are given choices they dun want. But they have to live with it for 3 - 4 years at least. Sadly, you can't excel in something not of your interest.
My friend wanted to be a doctor but was not successful here. He aced in his A levels but just couldn't make it during the interview for some reasons. Ended up studying something not quite his forte, Engineering, and ended up with a not-too-impressive Honours. Not surprising. Also given that his China lecturers spoke with hard to understand accent and explanations!
Another reason I have is that overseas lectures tend to be more lively and interactive. Over here, perhaps surprising for those who haven't been to uni, lecturers still let you copy slides word for word or even allow you to make copies of the notes! No such thing overseas. They want you to think, make your own notes and argue back and forth. Overseas they use toys, real life egs and a lively lecture to bring forth a point. Mine? A good many lecturers spoke with low boring tones and flashed transparencies. Stuffs which I'd rather read myself at home sometimes.