Here I give you some ideas that can work with teenagers and adults:
- Use English in class. (When they start learning it, they are not going to use them if they don't know it; that's why it's important to show them some key phrases which they have to learn for interaction)
- Be punctual. (Not only arriving early, but also handing work in on time.)
- Bring your materials. (Such as books, notebooks, dictionaries, etc.)
- Turn off your cell-phones or any distracting devise.
- Respect the teachers and classmates. (For example, be in silence when someone is participating, avoid the use of inappropriate words, etc.)
- Participate in class as much as possible. (To increase Student Talking Time)
Now, the question is: How do I make my students follow the rules? When teaching adults, we have to remind them that it's necessary to follow the rules to achieve their goals efficiently. I'm sure they'll understand because they truly need to learn the language. What happens with teenagers? In my experience in schools, it seems that at first, they need to know how concretely important the rules are, and many of them understand it by marks, or reports. It's not the ideal, but at the beginning it works until they realize that it's for their sake. But most importantly, you have to apply the rules in order to show that you are not kidding. It may be hard sometimes (sometimes we feel pity for our students) but we, teachers, have to be firm to get respect and have a good atmosphere (we don't want our students to feel that we apply the rules only for some students, for example.)
I hope that this was useful for you. Thanks for reading and sharing!