Pocket knives in schools?

I'm 13 years old and have been handling knives for a long time, perhaps 6 or 7 years (fishing, hunting, carving, etc.). I can't quite understand why an ordinary pocket knife isn't allowed on school premises. In the eyes of a proper user, such as myself, a pocket knife is a tool, not a weapon. In the state of Florida (where I live), a minor is allowed to posses an ordinary pocketknife with the consent of the minor's guardian(s). Why does this not apply to a school setting and why is there not a rule in place in which a student who has taken a proper cl and has teacher approval can bring one for daily use as needed? This way, no one who may use it in an improper way will posses one. School pat downs and searches would be appropriate, though, to ensure the safety of students and staff alike. Thank you for your answers in advance as I greatly appreciate it.