"Grades aren't everything, but they are important. They will affect your life later on. Until we can trust you to stay on top of things on your own, we will be requiring you to do 90 minutes of homework every night before you play. Even if you finish everything, we have other things you can do to fill that time. If we see any missing assignments, we'll have to add more time. Maybe in a few weeks or months, we can cut down that time, but you'll have to prove yourself."
That being said, to be honest I have really lightened up on grades. Even as a teacher, I think grades are so much less important than kindness and honesty, etc. My rule has been to pretty much allow any passing grade, but encourage straight As. Probably makes me look really bad as a teacher. Maybe I'm just tired of seeing straight A kids who kind of suck at being people.