From Kimberly Norton:
The speed limit in school zones ranges from 10 mph to 30 mph. The zones are posted with a sign and/or flashing lights. When school is "not" in session are we still legally obligated to drive reduced speed in school zones? This situation will usually occur on Teacher In-Service days, school holidays, Good Friday (when near a Catholic school), and about two weeks before the start of a new school year.