We need to turn custody over to my mom for our son to attend school in Ohio, how do we do that?

You will need to check what Ohio law will require. In New Jersey you would be required to do an affidavit indicating that your mom is caring for your son and that him moving there is not just so that he can attend a better school, but because you cannot provide care for him.   In Ohio you may need something different and at the very least you would want your mother to be able to get your son medical treatment in an emergency.  Good Luck.