Sonar, I'd get an attorney, and keep your boy OUT of school for the time being.
"She stated the student who brought it would probably be expelled."
1.So big deal a kid brought a (pocket?)knife to school, was he a known problem child? Schools will over look the serious problem kids who exhibit continous behavioral problems but expell a kid like this over ONE INCIDENT!
The other story where the teacher got into an in room brawl over the kids back pack being thrown into the trash can is pampered yet this kid will get expelled? Crazy stuff