The first two posts sum up the question pretty accurately: Most of these students don't care about their grades or are perfectly happy with the lowest possible passing grade. Motivating students to turn in their work on time was a full-time job during most of my teaching years, since most of my rural students never planned to attend college; they also seemed to think that only other people would eventually make a failing grade. Flagrant procrastination was a major reason for not turning in assignments in a timely manner; many students simply waited till the last possible minute to begin an assignment and then realized that time constraints prevented them from completing it on time. In many cases, parents don't seem to pay much attention until it's too late, preferring to accept their children's word that the work was done instead of checking it for themselves. And then there are the students who just hate school and every aspect that goes along with, and many students seem to feel that homework is some sort of punishment that puts a smile on teachers' faces when they assign it. Immaturity, procrastination, laziness and indifference are just a few of the reasons students make the decision not to complete their schoolwork.

One important point is auxiliary problems that affect schoolwork but don't relate directly to schoolwork as attitude and a sense of discipline might be said to relate directly to schoolwork. These auxiliary problems include health and relationship problems. Looking at health first, many students have chronic or as yet undiagnosed health problems that prohibit them from completing schoolwork.

While it is hard to believe in our contemporary age, many a student has undiagnosed or unmanaged chronic illnesses like hypoglycemia or asthma or chemical sensitivity that will interfere with their performance. For instance, undiagnosed or unmanaged asthma may cause memory to be impaired, which would impact both ends of homework, remembering to take it home and remembering what it is for once it gets there!

There is much brought to light about the sorts of relationship problems a student might typically suffer at home--parents fighting, etc.--but there may also be abusive siblings or neighborhood bullies. All of these things will impact a student's ability to perform schoolwork. And on the college level, as I know trophyhunter teaches at the college level, illness can still be a major factor that is worsened by being compounded by things like imprudent lifestyle or growing complications to the existing illness, like a roommate or floor-mate who drowns themselves in synthetically manufactured fragrance (do use essential oil fragrances like Yakshi Fragrances or Purple People Oil Emporium). Relationships also get complicated with some parents announcing the actualization of delayed divorces or with broken hearts from first serious romances.

So while a student's character and habits may be the cause of neglected homework or college studies, serious difficulties may also be the cause. I'm personally all for checking for serious problems first. In addition, at the college level, some students, like actor Jason Bateman, just want to go "wild" after being "good" for what seems like "so long."

Leadership in my school district is currently having a huge debate over the homework issue--asking questions concerning homework's continued validity in the classroom and whether or not homework actually strengthens students' understanding of the curriculum.  Many teachers are being encouraged to move to the "flipped classroom" model in which students receive direct instruction, notes, or modeled instruction from Elluminate or Blackboard sessions and then turn around the next day in class and work on what would typically be the 'homework' portion with teacher and peer scaffolding. 

The notion of homework goes far beyond a mere sense of social responsibility or even organization.  The largest single contributor to students not completing their homework is that it simply does not rate on their list of priorities for whatever reason: work responsibilities, social life, lack of parental support, belief that it will not jeopardize their ability to pass.  Students, like anybody else, will make time and remember and take care of the things that truly matter to them.

I agree with above posts that state the work has to be meaningful. Students needs to feel that the work they turn in should help them learn something important. Our grades are weighted heavily on tests, so students know that when they turn in a homework assignment, the grade itself is going to factor very little into their overall grade, but most of them still do the assignment because they know if they don't, they will do poorly on the tests, and if they do poorly on the test they can't do homework assignments to help boost their grade. I think there needs to be a paradigm shift in education. We need to go from focusing on grades to a focus on learning. This will be difficult as long as colleges accept students based on grades and parents push their kids to get A's even if the student is not an A student but is still learning.

Weighting tests much more heavily than homework is also helpful because students know they are wasting their own time if they do a homework assignment without alacrity or if they copy off of someone else. The old mantra "you are only hurting yourself" really rings true when they know they aren't even getting a large amount of homework points just for getting an assignment done. They still turn assignments in late, but they know to at least turn it in before the day of the test because, if they don't, the assignment becomes meaningless and they know I won't take it anyway.

I have to be very vigilant about homework and really stay on those kids who I know are bad about turning things in. If I don't, the homework grade won't hurt them, but they will most likely do poorly on tests and risk failing the class. It makes for a bit of extra work on my part, but it's worth it because I have a lot more success than I have in the past with this new system.

Below I have posted a link to an article that discusses the merits of standards based grading, as well as a discussion question I posted last year when I was still having a lot of the same difficulties with homework and grading.

I find disorganization to be a big factor for a lot of kids. When a student asks for an additional copy of any paper I have passed out, I always insist that they check their locker and backpack first, and at least two thirds of the time they find the original copy, usually at least partly completed, and sometimes fully completed. Why they don't look there before they ask, I can't imagine, but it happens all the time.

Another factor is denial. Many students have been passed along for quite a while before I meet them - I teach high school - and they have gotten quite used to second chances and/or getting by strictly on reputation, be it that of being a nice kid, or that of having a mother no one wants to do battle with. Regardless of the cause, the outcome is the same. They just expect that you are going to pass them, simple as that. If they fail, they expect that there will be a do-over. I wish I had a solution to this, but it seems like this sort of student will float along indefinitely until someone finally gives them a bad grade, or until they don't get promoted with their class, at which point many of them get the wake-up that they needed.

Some kids don't even turn in work they have completed. It usually is a symptom of a bigger problem. I agree that kids might feel out of touch. Sometimes they don't turn in work when they're failing because they don't see the point.

Although it may seem obvious, the first step is to examine the kind of homework that we assign. What is our purpose in giving a particular assignment? Are we providing students with adequate support in completing it? (see first link)

Besides assigning meaningful work, I always solved this problem by putting together packets of missing work with a list on top. I would tell them they could pass if they completed the packet. This accomplished two things. It reminded them that I cared, and it gave them a concrete path to success.

I teach in an exclusive private school now, so I no longer need to do this. It works though. I always told my kids I would do whatever it took to help them pass, and I never had anyone fail that agreed to work with me. It was a relief to them.

Many students simply don't care whether they pass or fail. Others think they can rely (and sometimes they are correct) on tests and other activities to bring up their grade. Still others simply can't keep up with everything they're required to do, perhaps do to lack of organizatonal and time management skills. And I have encountered many others who have to work or take care of children or younger siblings and simply don't have time, as they see it, to complete homework. 

I'd bet on two things.

First, they don't really care about the class.  They think the class is stupid and they have about a million other things going on that they'd rather do.

Second and more importantly, they don't really think that they can fail.  They think that they'll be able to make it up well enough later in the term.  Or they think that you'll let them pass because they're nice people.  Or they think you'll let them pass because everyone always has.