I switched to teaching physics mid-career, and after slogging away for a couple of years with constant disruption from my students have decided that I may just not have authority or "classroom presence". It doesn't matter whether the kids are bright or low-achieving they see me as easy game. If I give sanctions they argue back. If it's reached the stage that I ask them to go to another room they refuse to go: what's striking is that if I am able to call another teacher in these situations the students invariably obey the other teacher and go to the room. How else am I to interpret this but: "the other teacher has authority, I don't". My guess is that the only reason I am able to get jobs in schools is because of the dire shortage of physics teachers. Indeed I guess this might be why I got my pgce in the first place. I've stuck at it because I'm told that "behaviour management takes time to master". Maybe: but can I carry on till that "time" comes. I am currently working in a school through an agency, and I have offered to leave because of the problems I'm having. They say they are looking for a replacement teacher, but there doesn't seem to be one on the horizon. I don't want to leave them in the lurch, but should I just tell the agency I've had enough and leave? So, is it worth continuing to seek this elusive thing, authority?