My DC is at a progressive K-8 and will be in 6th grade next year. She's doing well in school but I have always thought math was a particular weakness at this school. I went to school in a large public school system where they unapologetically tracked the kids, so advanced kids were taking algebra in 7th or 8th. Here, there is an de-emphasis on tracking (though in practice they do differentiate). The information on how they teach math is frustratingly vague as there is no class called "pre-Algebra" or "Algebra" -- it's all just Math 7 or 8. Some kids are more advanced than others and math is very much a subject which builds on itself -- how are they going to be ready for advance HS math if they don't get an explicit class in Algebra?
Yes, I could ask the school for more info on it, but I don't feel like getting into it with them right now. And the school tends to be in line with other somewhat progressive schools in the city in how they approach things, so I'm hoping people can provide info on the general progressive private approach.