PC 626.10a covers k-12 schools and prohibits "any dirk, dagger, ice pick, knife having a blade longer than 2 1/2 inches, folding knife with a blade that locks into place, a razor with an unguarded blade." This leaves you with nonlocking folders under 2.5", and you might be able to get away with a hawkbill or other fixed blade so long as it is under 2.5" and it could not be used as a stabbing weapon.
PC 626.10b covers colleges and universities and prohibits "any dirk, dagger, ice pick, or knife having a fixed blade longer than 2 1/2 inches." So megafolders are OK there.
626.10(d) Subdivisions (a) and (b) do not apply to any person who brings or possesses an ice pick, a knife having a blade longer than 2 1/2 inches, or a razor with an unguarded blade ... for a lawful
purpose within the scope of the person's employment.
(e) Subdivision (b) does not apply to any person who brings or
possesses an ice pick or a knife having a fixed blade longer than
2 1/2 inches upon the grounds of, or within, any private university,
state university, or community college for lawful use in or around a
residence or residential facility located upon those grounds or for
lawful use in food preparation or consumption.
(h) As used in this section, "dirk" or "dagger" means a knife or
other instrument with or without a handguard that is capable of ready
use as a stabbing weapon that may inflict great bodily injury or
death.
For info on CA law, don't believe what people on the internet tell you, they're often mistaken. Go to the CA State Legislature's website
www.leginfo.ca.gov , click on "California Law" and search for what you want to find. You should get reliable penal code information there.