Do prisoners do anything useful in prison?
Useful in what ways? Useful to themselves? Yes, there are education programs available: anger management, parenting, moral reconation therapy, AA, NA, GED and so on... There are some programs that are provided by Employment Security that are designed to make inmates more employable when they get out. There are personal enrichment classes, religious study groups, physical fitness classes and team sports.
As far as useful to the public, yes to that as well. There are mandatory crews that work in public gardens, on the highways, yard work and landscaping around public buildings, public recreational trail maintenance, cemetery grounds maintenance, and DNR has inmate crews to maintain their lands, which includes inmate fire crews to fight forest fires.
Well, I have never been in prison, however, in juvenile detention there were a lot of programs / activities apart from education that I would count as useful. There were some workshops, a music band, even a theater club. Also, some of the typical counceling classes like AA and drug prevention programs.