My 9 year old daughter forgets things all the time. She'll forget her binder, she'll forget her glasses, she'll forget to clean up after herself. Basically, if something was supposed to be done, and she was supposed to do it, there's a good chance she'll have forgotten it. "But I forgot!" is usually the phrase I hear just before the reprimand comes. I can't be alone in all this. There must be a billion other parents who hear the same thing. Every day.
Why am I sure of that? Because I used to say it all the time when I was her age. It takes effort, but I have to remember that. I said it so often, my sister nicknamed me “Coma”. As a matter of fact, I said it so many times, I even developed a theory for it that I tried, unsuccessfully, to use to my advantage. It went something like... "But if I forgot, then I wasn't thinking about it. I can’t be disobeying if it wasn’t even in my mind. So how can I be faulted for not doing something I wasn't even conscious of?" Not bad for a little kid.
The fact that I thought it up in the first place though, probably means I needed to because I forgot so often. It helps me now when my daughter forgets something. I know I have to teach her responsibilities, but it helps to keep in mind that she's 9, and 9 year old kids will do that. It's been that way forever. Or at least since I was 9.