The limitation of L1 usage in efl classes can be obtained using certain techniques

The limitation of L1 usage in EFL classes can be obtained using certain techniques.

Firstly, a teacher himself should refrain from using L1.Some teachers have a tendency to use L1 especially while explaining a new grammar rule because they are afraid of what will happen if students don't understand?
Whether students understand or not the teacher should continue to use L2, but it should be suitable for their level.
Next, a teacher need to ignore a student who speaks his native language. As a result, the student makes an attempt to speak L2 in order to explain what he/she wants to say.
Moreover, a teacher can use SW method (silent way) in which the teacher keeps silence for at least 10-15 minutes and makes students speak. This approach creates a friendly atmosphere for students to speak more freely. Because when a teacher doesn't speak and doesn't correct mistakes students are more encouraged to speak

There might be two main reasons when a student falls asleep during the lesson. Either the student is really tired because of some reasons or he/she is not interested in the lesson.

First, conducting the lesson with some physical activities that are entertaining helps recharge and re-engage for both former and latter students.
Secondly, teacher should organise a group work activity which involves all students. It would be even better if this group work activity is educational and simultaneously physical.

Your teenage student is late

In this case, after class I call the student and ask the reason for being late chronically. As reasons can differ I try to solve the problem accordingly. Maybe the reason is related to his family if so I show empathy and let my student know the problem can be fixed. On the other hand, maybe he has difficulty in dealing with time management. Then I can help my teen make his/her own schedule or inform about how to organise an effective time-management by showing its efficiency with lots of examples in order to motivate to take an action. Sympathy and fixing problems together is better, I deem, rather than punishing the student in front of the whole class.