I have a planner book. I write down EVERYTHING. I have a really great memory, but I am always forgetting things like spanish homework and trig assignments. If there is a specific thing I need for that day, I also leave a notebook on top of my clothes that I lay out for the next day, so I see it and remember to bring that certain project or the markers or whatever for that day. On a daily basis, in terms of remembering things, I just only take things out of my backpack one at a time and put them back IMMEDIATELY or I WILL forget them. I know those things probably aren't all that helpful, though, as remembering things like that is not one of m major problems (probably due to the anxiety forgetting things causes me, lol). I also keep the pencils in a case, the other small things have their own cases a well. I used to keep every different subject's notebooks and such in its own big ziplock, but I don't need to anymore.
I am debating whether or not to ask this (because I never can gauge what kind of response I might get), but is your son in general ed.? How spectrumy is he? Some of these things will get him made fun of, if he is, like all the flack I took for the ziplocks and the post it notes everywhere. I am über organized.
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16 years old, I have synesthesia and Aspergers (probably) "I'm not a psychopath, I'm a high functioning sociopath. Do your research."- Sherlock (BBC)