But, the point is that I really believe that for many students it's not that they don't want to do your work. It's that they don't want to do your work when YOU want them to. Not all, certainly, but for some I believe that to be the case. They must get done with their own social life which is a much higher priority, isn't it? At 14 you're still exploring your world. When you're done with that THEN maybe you'll do this school work stuff.
If you're in a discipline where you encourage a lot of discussion then I strongly suggest that you establish a discussion forum in Moodle or Blackboard of in any of the free forum sites. Consider assigning fake login names so that they can post anonymously (except to you) so that they are free to really express their thoughts. Moodle has a great feature that lets you split a discussion post into its own thread. Perfect for when a student's response is provocative or insightful enough to warrant its own discussion.
When I heard it said again at PETE&C that study found that some students will go for DAYS without being asked a question in school, that made me (again) ill. At least a discussion forum will get that student expressing his/her thoughts.
Try it; you'll like it. (Name THAT slogan!)