teeagers are not easy students because it's no easy to keep their attention:)There is a wonderful website (you have to pay an annual membership) English Cambridge Teacher with a lot of material and a course dedicated to this topic . ciao AnnaMaria

In my simple opinion, let children be a part of a study which means participating in interesting activities in the class so that they can express their perspective, creativity and imagination.

This method is pretty effective when they get bored of textbooks. Good luck!

let some of them to play role of teacher so they can change boring activities to fun one but don't forget to manage the time, try to have and give fun by activities like games and songs ..
you can fined many in the internet like:

https://www.youtube.com/watch?v=ndZzqkC_LGE&list=PLGFFPLISoG5_vZQ_5uqc53-2tA1RWTNt9

https://www.youtube.com/watch?v=OH1ZKEwUCQY

https://www.youtube.com/watch?v=oEB_-rJRE44

https://www.youtube.com/watch?v=JxgyGEv4jvY

https://www.youtube.com/watch?v=RvrmPbubmOc

https://www.youtube.com/watch?v=iXHigR6Qe2k

Good luck..