I see my job as to make sure all the students in my room get enough math to be ready for the world with respect to college and career. Thus when a student does not want to learn, refuses to do homework, etc I do many things. One thing is for sure, a student is not "allowed" to sit and take an F in my room.
Not to say every student passes, but I also do not let 16 year olds make life decisions such as "I don't need math." or "I don't need a dipolma." I simply don't use grades as a motivator. If a student is motivated by grades I don't have to worry about that student's effort. If he or she isn't, well, then we have to find what does motivate them.
This year I have a few more students who are not too interested in school than usual. So the last thing I do is use a traditional homework/study/test class setting for those students. Given the opportunity they would cause disruptions, try to sleep (which I don't allow either), or some other less than helpful thing and simply fail. Again it is a young adult making a poor decision, my job is to help guide.
And since I believe what I teach is a key to their future success I make it my job to get them to do enough to learn what they need. That means all kinds of things, students staying before and after school. Students eating lunch with me (how cool is that - eating lunch with me - the math teacher!). Adjusting homework so we get what we need - everyone does not have to do it the same.
Now I hear teachers say that does not prepare them for work - for the responsibility. But school's number one job is to get them the problem solving skills, responsibility is usually something not learned at school - simply punished. And it is funny, the worst students can often be good employees - saw it many times. They realize the difference between a job and school and perform as required.
My job is to make school their job - forget grades - grades only prove knowledge by some instance in time, we are after them being ready for the world - that is not a grade thing.
So I keep on pushing, challenging, annoying and some of my students may dare-say harassing them to do their work - but in the end they need the skills and the diploma - and that is my job - to drag them through.