A common theme I get asked about during my workshops is student motivation, or student effort.
No matter what management techniques or systems you have in your classroom to maintain behavior, instilling a culture of working hard, or "grit" as some like to call it, is probably one of the most difficult things you can accomplish as a teacher.
A huge problem with traditional teacher-lead instruction is that the cycle of learning is "closed". You instruct, assess, grade, and move on. Students who don't want to do the work, simply don't try, turn in half empty papers, or don't study and fail. In the student's mind, it is easier to fail than to work hard for a short time and succeed (especially if they are used to this cycle and failing within it.)
By just stamping a grade on my students' papers, I was providing them with what I call an "Escape Hatch". For some students, it becomes normal to simply fail and "escape" hard work, so that is what they were inevitably doing in my classroom....