Is there a reason he must behave or act like a jerk? Or is he just taking it out on the kids?
I know he is "babysit" all those spoiled kids but that's not how you handle kids.
If you don't teach the kids kindly (praise them when they work hard) but keep insulting them, they will never open up, listen to you or learn.
Especially the kids who are going through rebellious age.
It also makes no-sense that he keeps all of important information for himself.
Tell those girls they are weak to make them be more careful, be more co-op, to make them willing to train themselves, etc.