The only way to get someone to do what you want is to make them want to do it.
I know that's obvious, but really think about it. What would motivate your son to try as hard in school as you'd like? We as adults look at it from a completely different view than children do--we look at how grades affect what college you can get into, things like that. Children, especially teens, think in the "right now". Benefits 5+ years in the future simply are not motivating.
Removing priviledges works to an extent, but it also breeds resentment. Plus, do you really want to be a warden or a parent?
The only thing I can suggest is that you find something that he really, really wants, and tell him if his grades are kept above a certain level, he can have it. You'll need to keep the reward schedule on close enough intervals to keep him going--say, every report card (assuming he gets one each quarter), he gets this reward.
What to use? That depends on your son. Money is usually good. (It has to be more than he'd normally be able to get his hands on, however). Trips. Concerts. New video game systems. Things like that.
The reward has to be good enough and come often enough to supercede his desire to be lazy and like everyone else (read:lazy
)
Good luck!
