I don't know if this would be feasible with your school (I know it wouldn't have been with our regular school), but my new system for DS11 in his e-school is showing all the signs of being a success on several levels.
With e-school, all the assignments and tests for each week are right there in front of him, of course -- it was extremely hit-or-miss to know what was assigned and when it was due last year with the regular school. However, the assignments are still scattered among all of his seven classes in the listings, and he has a habit of cherry-picking and then staying up late in a panic to finish the things he put off because they were worse.
Anyway, I got him a weekly planner where the whole week is across two pages, in columns. On Monday, he wrote every assignment for every class in that column (and it ran out of room and squished into the bottom margin). Everything that had five or more days to go, he highlighted green. Everything that had three or four days to go, he highlighted yellow. Everything that had one or two days to go, he highlighted red (pink). Everything that he did that day, he crossed off, and what was left was rewritten into Tuesday's column and highlighted accordingly. And so on through the week.
My plan for this was to show him what happens when he lets things pile up, with a highly visual demonstration. AND to show him at a glance which things he needs to do first, because they are due soonest -- pink is going critical, yellow is getting there, and green can wait till the others are done. He's picked up quickly on prioritizing with this.
The other bonus is that he can see how much work he's put in this week, as the list has dramatically shrunk down to just a few things by today. He feels good at having accomplished so much, things are getting done in proper order, and if he falls behind as new assignments come in, it will be immediately obvious.
I know this doesn't necessarily help with the "getting things done instead of doodling while you're supposed to be working", but it might -- because there's a very tangible picture of what's left to do and how long you have to do it.
We couldn't have done this in his classes last year, because a great deal of the problem was that even with the Power School system, the teachers weren't that great at posting everything that was assigned AS it was assigned, and he was predictably awful at remembering that he had anything to do. He's never managed to use the regular planners that the school gives out every year.
