Great eply from @Volant
She is being punished for her autism, yes. Organisational skills are incredibly hard for autistic children.
DS2 has HFA. No amount of reminders will help him remember anything. That part of his brain doesn;t retain as other people's do. And punishments definitely won't help him think "won;t do that again.' because, again, that's not how his brain works. He'll just think: 'They hate me,' feel scared, demoralised and the resulting anxiety will make him even more forgetful.
We found setting up a system for him really helped. IN case it helps your DD, @102910h here it is:
Get school to provide you with a copy of her weekly timetable, homework timetable and email addresses for all her teachers and form tutor.
Get a big plastic crate and put it in the kitchen. All school work, books, and textbooks go in it.
Buy a stack of ziplock A4 file bags. Label one for each subject. Put textbooks, exercise books and loose sheets of paper into them. This is the single most useful thing you can do, as she only has to hunt in one place for one ziplock bag for any given subject.
If a subject needs specific kit eg coloured pencils for geography, protractors etc for maths, add those to the ziploc bag. Then if she loses her main pencil case, she still has what she needs for those lessons.
If it helps, add a pen, pencil and small ruler to each ziplock bag.
Print out 3 copies of her timetable and highlight all the lessons where homework is supposed to be set. Stick one in the kitchen, one in her bedroom and one, folded, in her inside blazer pocket.
When DD comes home from school, help her empty her school bag every evening.
Check her homework diary with her immediately. Usually DS would have forgotten to use his homework diary. But if you ask the day it was set he might remember, or could email a few friends or the teacher and ask for a copy of it. Get her to write what it was into the diary anyway, so she has a full record in a single place, of what she should have completed throughout the term.
Help her sort out what she needs for each piece of home work. When she's finished the homework, check that she puts everything from the subject back into the ziplock bag and the bag back in the crate.
Every night, get her to check the timetable and pack her bag. Check her bag with her. If there are extras e.g. gym kit, swimming kit, music bag and instrument etc, help her get those packed and when all is done, put the lot by the front door.
This all sounds a bit fussy, but it's no fussier than having to remember to put individual things into the bag. When we started this system, (in Yr 8) it immedieately made life easier for us all. We could see at a glance what DS needed with him on a given day.
The only downside is he never used his locker. He couldn't, because he had to lug everything with him. If it was in the locker, he'd forget it. It all came home every night. But he never lost anything from then on. Never got another detention. Rarely got swamped by overdue homework. And by 5th form, when it really matters, he was slinging stuff into his bag within seconds, he was so used to the system.