There is no such requirement, I wish there were.
In San Diego and El Paso and other cities there are buses that pick up Mexican kids at border crossings so they can attend US schools and go home after school.
Most school districts will not reject illegal aliens at all when they apply.
Yes, I'm aware of that. Picking up Mexican kids at the border to go to American schools is particularly obnoxious. Displaying Mexican flags in those American schools adds insult to injury, especially when you consider who is paying for these Mexican kids' education.