I am an elementary school principal. Here are some of the things we have done with our students:
1. We issue every student an assignment book at the beginning of the year. Not only do the students use it to write assignments, but teachers will write a note to a parent in it rather than on a loose piece of paper.
2. At the beginning of the week, I include as a part of the morning announcements over the intercom events coming up during the week.
3. We ask parents to look at the planner every night. Since we do this for every classroom in every grade every year, it's something that has become part of the school culture.
4. We encourage the students to empty the bookbag totally when they get home (so things don't sink to the bottom, never to be heard from again). So, I guess we are teaching them to collect in the bookbag, then dump it all out and process at home.
5. We encourage the students to decide (along with their parents) on a spot at home where everything that requires Mom or Dad's attention will be put. (We don't use the term "in basket," but that's exactly the concept. When Mom and Dad finish with the material and return it to them, the students take whatever action is needed, and then put it in the bookbag.
We have not gone as far as organizing tasks by context. Everything goes on the calendar, but I really think at this age that's the best way. Just as many of us have progressed from the daily to-do list to GtD, I think kids need to go through the same progression. (I have written an article for principals that is pretty much GtD as it relates to the principalship. David has a link to it on the "Press Links" section of the site. It's the very last link.)