Prison Architect allows you to enact a number of different programs to help reform and educate your prisoners. Two programs in particular utilize a classroom: Foundation Education Program and General Education Qualification. In order to have these two programs run smoothly, you’ll need to build a classroom and its minimum amount of objects.
Once you have that, simply start up the programs and make sure you have enough Work slots through a day in your Regime to incorporate them into your prisoners’ lives. It’s as easy as that, a teacher will automatically come each day in time to teach the students, no need to hire one from a staff menu.