I am sure your friend is a great teacher and I hope it helps some guys when they get out.
As far as public school teachers, the ones i’ve known had IQs up there with bricks and asbestos
He’s been involved with prison ministries for quite a while and has hired a number of ex-cons over the years with varying success. This is a new gig and the challenges of dealing with the establishment is killing him.
Those who can, do
Those who can’t, teach
Those who can’t teach become school administrators.
My brother teaches pre-engineering, CAD etc at public school. The challenges with administrations are insane.