Not a lawyer, but I have carried when the facilities haven't been used
exclusively by a school district. Such as a Church event, non-school district hosted function etc.
http://apps.leg.wa.gov/rcw/default.aspx?cite=9.41.280Quote:
(1) It is unlawful for a person to carry onto, or to possess on, public or private elementary or secondary school premises, school-provided transportation, or areas of facilities while being used exclusively by public or private schools:
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Of course, then there is section (6).
Quote:
(6) Except as provided in subsection (3)(b), (c), (f), and (h) of this section, firearms are not permitted in a public or private school building.
Easy answer is, who knows....