A friend of mine in grad school actually used to teach drama and do performances in prisons. It isn't all that uncommon. Generally it's a form of drama therapy - it allows the prisoners to deal with the consequences of their crimes, and other life issues through art - something they often won't do with psychologists and councillors, but which they can through artistic outlets.
"It is a good divine that follows his own instructions."
Merchant of Venice, I.2
"If making oatmeal cookies with bugs instead of raisins is wrong, then I don't want to be right" - Bucky Katt