Ohio Rev. Code Ann. § 3313.481

Wherever in Title XXXIII of the Revised Code the term "school day" is used, unless otherwise specified, that term shall be construed to mean the time during a calendar day that a school is open for instruction pursuant to the schedule adopted by the board of education of the school district or the governing authority of the chartered nonpublic school in accordance with section 3313.48 of the Revised Code.