The article you linked is incredibly confusing. I assume the issue is, which is typical of any advanced courses in school districts where helicopter tiger moms live, that little billy didn't qualify for the advanced math course because he's not smart enough but mom knows he's actually a genius. The pressure to let in little billy builds and builds until the districts relent and fill the classes with buffoons and the educational quality is lowered for everyone.
The crux is that many students would take the 9th grade math course via private courses to then jump ahead a year or two when they get to the high school. The school tried to prevent people from doing this and the parents sued.
I went to this high school ~10 years ago and at the time a handful of kids every year would do this. I'd imagine it's much higher now though.
The lawsuit was filed because (1) the district refused to allow students accelerated placement based on their prior outside coursework, and (2) used acceleration exams with a pass threshold that was comically too high (requiring students to know much more than was actually taught in the classes they sought to pass out of). These tests ended up having a wildly disparate impact on girls, who passed at a much lower rate than boys.
The district lost on (1) but not on (2) because it is illegal in CA to refuse placement for a student who has completed a course that would qualify for UC/CSU credit — which is what PAUSD was doing.
In 9th grade, to accelerate from Geometry to Algebra 1 (10th grade) you needed a 95% on the exam, which was 1 hour long and around 90 questions. And this was despite taking Algebra 1 and 2 at a certified private school with UC/CSU credit that the C-suites of Tech companies send their kids to.
Why would you accelerate from geometry to algebra 1? Do you mean algebra 2?
My understanding is that at PAUSD they had two tests, one part that measured if you understood the core curriculum, and another that was more along the lines of brain teasers/math competition problems. You had to pass both (many passed the first but not the second). One issue was that the district seemed to cherry pick students to let them through; students would get access to accelerated classes even if they scored worse than other students who were blocked.
It sounds to me like there may have been an intermediate step, which was for little billy to be enrolled in some sort of third party course as a catch-up / qualifier for enrollment in the advanced class, and the district not accepting that.
