Are school bus drivers elgible for overtime compensation under Ohio law?

I work at a school as a contract bus driver. Must point out, wer are not a unionized operation. Our base route is approximately 15 hours per week. We have senior drivers who take an additional contracts of 2-3 hours per day for special education and other shuttles, which bring their total hours per day to 5-6. Also, the school has numerous sports trips and school field trips that driver may sign up for. Our senior drivers, who take these sports trips, extra shuttles, and extra routes are they elgible for overtime pay on hours that exceed 40 per week? We are told no becaue of several reasons: 1. The hours must be in the same department; 2. We are not classified as full time full year employees; 3. Just because. Are we as drivers entitled to any overtime pay per the law?