[X] Philosophy. It would be helpful if she knew how to structure a logical argument, and you're also somewhat curious as to what the ethics of a [Slaver] are. If there are any.
[X] Write in: Subtly interrogate your students for information on topics related to your current location, jailers and popular classes and skills in the region.
[X] Talk to the other slaves to learn more about this world and how it works. Your understanding of reality is obviously not 100% applicable to the current situation.
[X] Basic Physics. They probably have all made observations about the active forces that hold the world together, but you'd be surprised if they had ever made any head way into the subject matter. Introduce them to leverage, gravity, and the reciprocal nature of force.