well, one of the things that I do is I summon parents and try to discuss with them their children �s behaviour and see what are the things that make them behave like that and try to come up with a solution. You have to know that sts don �t like their parents to be aware of what they do in school, so when you do once call a parent, all the other sts know that if they do sthg wrong, you will call their parents too so they calm down and focus more on their studies...it does work like magic I swear .

the other thing I do is I sometimes invite the parents of disruptive sts to attend the class with their children..imagine what the sts would feel........some sts don �t like their parents to walk them to the school, let alone attend one of their classes......so they prefer to be good sts than being obliged to put up with such humiliation (for the sts but for me it �s sthg that all boards of edu should adopt)

try at the beginning of the school year to give sts a profile sheet where they write all the information you need to know about them,for example their favourite movies and songs and also their parents � address and phone number so you can keep in touch with them...just knowing that the teacher has their parents � number and address make them behave well. try to check the correctness of the info they give u from their files at the administration.

try to speak only in english in class and don �t give them a break; work work and work.when you show your sts that �s it �s not a vacation and you are serious abt your job they get serious too. you may also create a sense of competition between sts and reward them so they can focus on their studies to get that reward.

and when you feel that your class is back on track, start doing interesting things like songs,movies with popcorn (i love those days), read stories with them (you can even create a book club), try to attend one of their gym classes (they just laugh when they see their english teacher trying hard to dribble the ball....hilarious), and of course some treats to offer them when they give correct answers (chocolate is great) 

I hope this helps and if you have any other question please do ask ...feel free to PM.