Oklahoma's Algebra exam requires a 70% to pass = a D, so a Charter school could conceivably have all it's kids average a D+ and honestly claim they had a 100% pass rate. Kids could pass the easier parts of the algebra exam and fail the more advanced sections and still pass the final exam. Nothing to brag about.
IMO, all these tests are just quasi IQ tests, which employers would love to have , but can't get. I once took a MASS test for a job at a powerplant and passed it. It's the test that subtracts wrong answers from right ones, which is the kind of feedback you get for mistakes in the real world.
The way teaching works, is my daughter has passed every math class through the 9th grade( extra credit helped)- and even algebra this year in HS, but she failed the end of course exam by 7pts, so she is in summer school and hopefully she passes the exam in 3 weeks- it's a graduation requirment. She remarked how much better this teacher is than the one she had for the course.
As I tolder her, English is more important. An employer may not now or even care that you scored poorly in algebra, but they will quickly figure out you are a doofus in English- poor English might even keep you from getting hired.