The US public school system is not designed to educate. They repeat lessons in such an obvious way that it's equally obvious that they have another agenda. That agenda is twofold:
1. Keep the niggers off the street until it's legal to jail them as adults. Then you can just throw away the key.
2. Since the niggers are already dumb, you don't have to worry about them getting smart. So, the 2nd part of the agenda is to make most of the remaining, non-nigger kids into drones who largely obey orders.
In public schools across America, math "teachers" are busily repeating the most boring elements of math education, and are trying to obtain the strongest, anti-education reaction from the children. These "teachers" are merely jailers who are trying to get the inmates used to the sight of the bars on their social cage.
When a school or educational system is freed from this system of propaganda and control (i.e. pre-imprisonment), then real education can happen, and you'd find that pre-high-schoolers (grades 6-9) are perfectly capable of handling strong algebra, and the minority of those (the truly exceptional) are capable of handling "college-level" calculus at such an "early" age.
Poster #3 had it right, and I'm only following-on to what was said. The public school system in the US would never tolerate this depth of education. They only want to collect their FAT paychecks, benefits, and retirements ... while they prepare the niggers for prison and the rest of the children for corporate slavery.