Our school requires an exit exam aka placement test every year for Math classes starting 3rd grade and continuing through HS. It is possible for a kid to take Algebra or another HS level class, get good grades, and fail the exit exam. They do get a second chance at the test in early August if they fail in the spring. They recommend retaking a class or non honors track to students that fail the 2nd test. It doesn't happen often, but it does occasionally. It keeps the teachers in check from grade inflation.
I would inquire if all students are being assessed or just yours. In our district all of them are being assessed every year.
