I want to limit screen time but then when I see him asking for certain programs I become so torn.
I think that I'm going to set a scheduled time each day, with a time limit, that is for entertainment purposes. If he wants to play Angry Birds or Temple Run so be it, though he really like Presidents vs Aliens yesterday. At other times when the usage is for educational purpose I'm going to try and relax my concerns and see where this leads.
I would be very careful about this, because you may be drawing a distinction that he has not yet made. He may find Khan Academy to be every bit as fun as Angry Birds. If it occurs to him that Khan Academy is "work," he may lose interest.
FWIW, my DD8's usage of the computer mostly consists of simple flash game sites (y8, girlgames) and browsing Youtube for funny videos (fails, song parodies). In other words... mental junk food. We don't worry about it, because she's challenged in (home)school, she has other activities where she's challenged mentally/physically, she spends a significant amount of time in free play with friends/parents, and she self-regulates her screen time to just a small portion of her day.
And that, I think, is what you really want to be focusing on here... when your DS is on the computer, regardless of whether it's mentally nutritious or junk, what else is he missing out on? Is he spending enough time in free play (which is VITAL for proper brain development)? Is he losing out on interactive time with peers and parents? Is he getting enough exercise?
The major problem that studies of screen time and children identify, time and time again, is that excessive screen time crowds out other necessary, beneficial activities. So, if you've identified a lack, then it becomes necessary to set limits. If not... no harm, no foul, right?
