Selective schools test to find the most capable young students. There are many arguments for and against this. Some arguments question whether or not the more capable student should be put together; some question the selection method.
One criticism leveled at selective schools is that the individual students suffer cultural shock when they realize they are no longer the smartest kid in the class. This is undoubtedly a huge adjustment, but it’s a necessary and humbling one; and something better learnt sooner than later. If a child realizes that there are minds smarter than theirs, as well as minds less capable, then they are getting a realistic perspective. It would be far worse for the student to have delusions and overestimate their ability. This criticism confuses self-esteem with superiority. A child and well-adjusted adult needs to feel valued for being a fellow human being, for achieving goals; not for competitiveness and trying to outdo others. Selective schools are beneficial this way; the child knows there are others at the same level as him/herself, and that this is perfectly acceptable.
A more valid criticism is that the selective criteria for these schools are poor; that the tests cater to coaching and rote learning. While this is true it must be remembered that it is quite difficult to have a completely impartial test. It must also be remembered that rote learning is part of the practical world, and being prepared for exams (coaching) is also a reflection of real world situations. Tests are not just about intelligence, they are about motivation, time management, preparation, and the notion that some things are true even if they defy analytical thinking. If a child can prepare itself to do better, then it deserves some support.
A variant criticism of the test criteria is that the children can be coached to do well. This is partly valid, as coaching is a considerable help for many children. But this is only bringing a child to its potential. If the coached children did well in the entrance test only to fail at the school we would have cause for concern. There is no evidence of this. Academic coaching is like sports coaching in this regard; get the best possible performance from an individual in a specific pursuit.