Ah thanks for all your replies - I really appreciate it!
I've taught this group 4 times before, being observed by their original teacher, so I know them a little bit. I knew I had to go in strong as I had been far too soft in my previous lessons and they'd walked all over me.
I had ground rules ready and waiting written up on the board when they came in, and we spent the first part of the lesson talking about that, and they seemed to like the fact there were rules, particularly when they could shout out about a friend who was breaking the rules.
One of the main ways I lost control was near the end of the lesson, when they realised that the 3 strikes and out mobile phone rule didn't matter as we were all going home soon. So loads of them got their phones out. I couldn't write all their names on the board so I just ignored it.
Things had been degenerating all day, and the last task was a team quiz, where I would normally write team names on the board and record the scores. One student who is usually quite good wrote a really rude team name, as I was standing right next to him. I just ignored it, and didn't write any team names on the board But looking back I should have really disciplined him for that.
I am teaching a subject they don't particularly care about, and I have them for 4 hours one day a week. So it is a long time for a boring subject. I know I could jazz it up somehow but I've got to learn all these lesson plan tips as I go along.
I've observed their normal teacher with them and she is very strict, I was taken aback the first time, but that's what I need to get to.
They have been sitting in groups of 4 round a table, but I'm going to try horse shoe or L shaped as recommended. I've tried dividing the groups lots of times in my lessons, but almost all of them are just as bad next to each other. There's only two quiet ones in the group who don't cause problems.
Basically right from the start I started weakly. They were all waiting outside the classroom, and at 2 minutes to go I opened the door and said 'Start coming in.... when you're ready' I shouldn't have added that last bit, as then they didn't come in for another 5 minutes and I had to go out and get them. Then the student who had been closest to the door when I originally opened it, decided to go to the loo. And all the boys had a great time telling me he was going to do a dump, he later walked into the class 10 minutes late, and I couldn't challenge him.
What would you do if boys were telling you their friend had gone to do a dump? I ignored them, but what should I have said?
I've not started teacher training yet, I was hired as the college were actively looking for people with industry experience.