Ohio Rev. Code § 3309.30
For service subsequent to June 30, 1955, the retirement board shall credit a year of service credit to any member employed on a full-time basis for nine or more months of service within a year. For contributing and prior service before July 1, 1955 only eight or more months of service on a full-time basis within a year will be necessary for a year of service credit. Effective July 1, 1977, full-time service is defined as one hundred twenty or more days of school service during the school year. If less than one hundred twenty days, such service shall be prorated on the basis of one hundred eighty days. The board shall adopt rules as necessary to carry out the intent of this section. The board shall credit not more than one year for all service rendered in any year.
R.C. § 3309.30