I'm homeschooling my kid and have been using sample problems from both Russian and Singapore math. But I only have a single source for Russian math problems, which is a pdf of a paper by a Russian educator who taught in the US and then wrote a paper comparing the two educational systems.
It's interesting because he talks about how algebra is a big scary subject that is introduced late in the American system, while in Russia they start doing algebraic-type problems early in primary but they are solved with pictures. So when algebraic notation is introduced later it's just a next step to the types of problems that students have already been solving.
Also: https://www.ocf.berkeley.edu/~abhishek/chicmath.htm Also: https://news.ycombinator.com/item?id=18360071
If you look at another of my response comments to my parent comment, I mention that I don't really know if the system could be replaced with something better, but I don't think standardized education is good for anyone when compared to non-standardized education.
While true, I just don't think a one-on-one education, however skilled the tutor might be, could possibly match the social development that comes as consequence of classroom education.
I admit that their ability to not embarrass themselves among their peers is greater than those who are homeschooled or from experimental private schools, and their traditionally-schooled biting, ironic sarcasm is unmatched among the more naive non-schooled population. Traditional schoolchildren are also much better at taking instructions, falling in line, acquiescing to the wishes of their superiors, and bearing assaults on decency and freedom without complaint.
I made it through 12 years of public school and am extraordinarily "well-socialized", and I am disgusted by what it took to make me that way. It's only now that I've been out of school for about a decade that I've finally started to turn into a human being.