The curriculum already exists. Textbook selection is already done. The discussion is about delaying teaching a subject, not eliminating it. You don't need more materials, just different ones (one additional algebra book and one fewer remedial book). And you don't need more teachers. Just be more effective about grouping the kids the teachers are already teaching. My suburban school had no problem putting together multiple sections of algebra in middle school. I'm sure a city with 10x the population can do it too. And if a teacher can't teach basic algebra, they probably shouldn't be teaching math at all. Or if you mean later classes like calculus, let the kids leave, and if there's a local community college, allocate some of the money you saved to let the kid take classes there.

> What’s left is just a rather weak argument about not letting them get bored. Solving boredom should take a back seat to solving education for the less fortunate, IMO.

Okay, then let the advanced kids go sit in the library, go outside and play, or go home. Making them sit in class is, if anything, going to make them anti-social and create resentment toward the "dumb" kids. I don't think torturing a kid making them sit bored out of their mind among people they don't like for 15% of their life for no reason is a "weak" thing to argue against.