Den Begriff "504 students" im in #0 verlinkten Artikel musste ich recherchieren. Offenbar handelt es sich um einen US-Ausdruck für Schüler mit Behinderung, die an der Regelschule unterrichtet werden ("inklusive Bildung"):
Section 504 of the Rehabilitation Act of 1973, commonly called "Section 504," is a federal law that protects students from discrimination based on disability. [...]
To be protected by these laws, a student must have a physical or mental impairment that substantially limits one or more major life activities.
Under Section 504, students with disabilities can access the accommodations, aids, and services they need to access and benefit from education. Section 504 requires that public schools provide a "free appropriate public education" (FAPE) to every student with a disability - regardless of the nature or severity of the disability.