I want to be a better substitute teacher so that I can be a more likely candidate to sub and be a candidate for a full-time teacher. But I have problems with subbing for Middle and High Schools. Whenever I try to give an assignment, it seems like the students are doing it but they just talk and not do the work. Some students do the work but others don't. I try to tell them that the assignment is for the grade and that it's due at the end of the day but it's like they don't care. I don't know how else to motivate them. I can't give detentions or any punishment like that. I want to be able to get students to do the work and do the test but it's like I don't get any respect even when I look serious. What can I do?