I think it also depends on what set you're put in. If they are called sets anywhere outside the school I went to!
In my school there were seven sets - classes teaching at different skill levels - for each year group for maths, science and English. While all sets had to follow key stage work, kids on record as being better or worse at a particular subject would be put in a higher or lower set, and in some cases that meant the meat of what they learned during a given term might be different.
I don't know if it is still the case, but in my school when we did our GCSEs, the set you were in during your final two years of school could limit the maximum GCSE grade. In our school only the top set, and the best half of the second set, were given a version of the test papers that even made it possible to achieve an A grade, because only their papers had the hardest questions in. Those in the bottom half of set two or in set 3 could, at best, get a B grade. Then C grade. Kids in the bottom sets could basically, at most, get a D. I remember I always thought that was wrong, since it meant kids were being limited as much by class sizes as they were by actual ability, and I imagined it'd be pretty damn disheartening to know before the exam that it was impossible for you to get the highest grades.
Do schools still do that?