Alternatively, if you keep kids in a terrible school it becomes a hell of a lot harder for them to improve and live up to their promise than if they'd simply been moved to a better school.
Which is worse?
Well, from a purely theoretical view, Scenario A focuses on a select few kids and gives them the best possible education, but the kids who initially seem less able have a much smaller chance of proving themselves. Scenario B tries to focus on everyone and gives kids more opportunities to improve, but doesn't end up giving as high quality education to the best kids. I would argue that A results in a much higher stratification of society - more kids end up lumped into "doing well" or "doing badly", with less of a spectrum, while B ends up with a better spread and more kids clustered towards the middle.
The plus side of A is that if you look at the american example, you see that it gives you a big advantage in technological advances, hence Google, Facebook, Microsoft etc all being invented by students from the top tier of american education. However, you have to weigh this off against the social problems that arguably stem from americas inequality, such as crime, teen pregnancy,
religion, poor mental health, etc etc. More equal european countries such as sweden, denmark, norway, austria, belgium, holland etc have lower instances of social problems such as the ones listed above, but arguably also result in less technological advancement. Germany has a weird system whereby they do segregate people off into different schools, but the less able kids focus on professions such as plumbing, construction, carpentry etc and don't neccessarily do worse financially out of the system.
As a country we have to decide which model to follow - focus on everyone and hope the equality itself benefits us enough to justify it, or focus on an elite few and hope their intelligence ends up benefitting everyone more than the equality would have. Both are a gamble, and neither deal with our reliance on the banking industry in the short term, but I personally favour adopting a more european approach than an american one - focusing not neccessarily on doing what they do, but on achieving through equality what they appear to achieve, with perhaps a larger emphasis on professions for the less academically capable kids in our society.
Here endeth the rant.