In order for a teacher to really have control of their children, there are certain classroom management techniques that need to be used. Every single teacher is going to be different, but these techniques can be very beneficial.
The first step is to really understand the type of kids who are in the classroom. If they are a younger group, they might not respond the same way as teenagers. It can be very frustrating to move from different age groups, But the good teachers are going to be able to make changes.
It also helps to get assistance from other teachers as well. They might be able to really inform others how to handle certain types of classes. Maybe they had them in the past, so they know what works and what does not work for them when they need to really be paying close attention.