V.P.
You noticed that about half the class is below where they should be -- that's correct. Because that means the other half is at or above. That describes a curriculum that teaches to the average. My kids tested in the 99th percentile for reading every year, and they are bored out of their minds. It's not the fault of the school, but the school does try to find alternative assignments for them. But if the classroom curriculum taught only to those 12, my kids would absolutely hate school. Meanwhile, my daughter struggles in math. It's not the school's fault, because she has kids in her class that are advanced in math. She's on the low end of average. So it's up to the school to be patient and help her and up to us as parents to find support for her -- so now I take her for tutoring once a week.
You wouldn't have remembered kids struggling in school because most kids won't tell their friends about it -- that's not what recess and playdates are for at that age. But when classrooms have 20-30 kids per room, about half will be below average and about half will be above. And if the kids are going to advance, the curriculum should always be slightly above average.