Ask about the knife or don't get caught it could be bad things... or nothing at all? I don't know about your school.

When I was in high school we carried pocket knives at our own risk. Some teachers did not care and we used them in class as needed others would have surely suspend us or reported us to the principal.

Your kit sounds good so far.. at a glance I would add:
AD pills.
Food. (power bars, beef jerkey, etc.)
Water.

More to come.