My daughter has started just leaving things where she stands - things like food wrappers and orange peels. I have pretty much treated it as I would remembering to the flush the toilet.
I started by explaining why this is a problem.
I've consistently and patiently reminded her - and don't clean it up for her.
I've asked her for ideas she felt would help her remember (she didn't offer up anything other than, "I just need to remember, Mommy - I'll try harder."
Obviously, I set a better example then that and clean up after myself.
In the past, things like this (toilet flushing, hand washing, turning off lights, etc. have come and gone and this method works and by the time a few weeks to a month has passed she has either outgrown the "forgetfulness" or learned what she needed to and we've moved on. For some reason, this particular habit has had a staying power the others have not.
I Do NOT WANT ideas for PUNISHMENTS please - no suggestions of spanking or smacking . . .
Update:
Okay. She finally grew through it. Seriously, I didn't change a thing and all of a sudden, not a problem for the last two days. She even dropped a bag of flour that burst open in the kitchen tonight and when her dad started sweeping (because I was stir frying) she said, "Daddy, I should be responsible for that. I spilled it." and helped him sweep it up. She also gathered up her stuff at the theater quite nicely Sat. night AND hasn't left any sort of wrapper or food sitting anywhere it shouldn't be all weekend. She even cleared her DAD's dinner dishes tonight (Monday) for him. Go figure!