Yes I understand that, but the sample unit called out in finding the median explicitly was 'schools' not median 'state.' (And before that, test scores, in which the fundamental unit is a child and not a state).
I was trying to come up with an explanation how CA could be at the bottom while still have schools around the median.
If NY/CA/FL/TX are huge and tight to together, the median school or child could be in one of them even if they were amongst the worst 5 or 10 states. The 'median' as used above was in reference to schools, not states.
I think the key piece you're missing here is each state does not have equal number of schools or children. Therefore if a state's schools are all scoring near the median (of schools) as alleged, and the large states are all doing bad, California could be one of the worst few states while having their schools (and children) near the median. You're getting your units mixed up.