Help needed with teenagers

Do they actually want to be there or are they being forced to come? Are they "good" kids who just don't have any english or are they just really uninterested? For my teenagers who speak too much of their native tongue in class I had to start a "no (native language) time" rule. I used this primarily in the 'study' portion of the class and gave them some more freedom when it came time to learning games or free conversation. Basically I kept a score sheet and they lost or gained points if they spoke their native language. (and if their friend tells on them the friend who tells gets a bonus) It worked really well and I used the points to either give them more homework, give them a head start in a game etc whatever you want.
Just an idea

I teach 11-15 yr olds in France and the 14-15 ones are the least interested for a variety of reasons (need to look into teen psychology there). Motivation is the big factor. I assume, as in my case, it's a state school situation with English as a compulsory part of the timetable. If this is the case, being firm (but gentle of course) is the first thing. You can't have pupils coming out of maths with a strict teacher and then expect them to spontaneously flourish in EFL. You may also be using a text book which may or may not be of any use. Make your own material if so. I did the US elections (although it's a bit late now) but you can still do inauguration day (research, web quests, information gap, writing biographies...) or anything topical really... If you have to mark them for their report card, tell them they will get points for not speaking Spanish, for using 'classroom English', for participation in oral activities and even for good behavior if they're really bad. Also, never start a lesson if there's any noise and never raise your voice. Remember, you're the adult. Yes, you can!... Now who said that?

Mary1 this sounds like one of my classes! I also teach some teenagers in Spain. I have two groups of about 13/14 yr olds that are doing a coursebook for PET(so the courseboo doesn´t really appeal to them much!). One group is much better than the other. I´ve tried doing extra activities for communication but most of the time they don´t listen, talk, do the activity in Spanish etc. I´m at my wits end and usually end up stopping the activity and going back to the book. I´m thinking of trying a no Spanish policy as suggested and see if that works. I feel like I can´t do anything fun as they just don´t seem interested in anything!Would love any further suggestions of how to turn this class around!