So, I sub at a high school that generally has very well-behaved students. Today, though, I subbed for a teacher that is known to have a couple difficult classes. Well, these two students kept disrupting the overall quiet and working class. I gave them two warnings and warned them that they will be written up if they continue to be disruptive. I did right them up, and that seemed to stop the disruptions. I hate having to write students up, but if they're being a disruption and won't respond to my usual classroom management techniques, then I see no other way.