The PC states K-12 "inclusive." So, any single or multiple of those grades qualifies as establishing a 'school zone'
So, any 'school' providing instruction in any of those grade whether public or private would qualify.
.gov public schools - definately qualify
private schools - definately qualify
charter schools - these can be either private or .gov - very likely apply
home schools - I would say these definately qualify, but this is where 'reasonably knows' becomes invaluable.
preschools - not K-12 - doesn't qualify
I don't have a clue what a "head start" school is...
626.9 (e)(1) "School zone" means an area in, or on the grounds of, a public
or private school providing instruction in kindergarten or grades 1
to 12, inclusive, or within a distance of 1,000 feet from the grounds
of the public or private school.