Why Do kids do, what they do?

So today at my lil girls school, it was the last day for the book fair and I asked her teacher if she could send Anna down when they had some down time. So then before lunch here comes Anna, all excited because she gets to finally buy her books and has she was heading back to class, I said to her "Anna when you get to your classroom put your books away!" and I was told she did! But when she came to the library after school because that is where I was, helping pack up all the books. She sits down and pulls out her books. I then tell her "no put your books back in your backpack and do you homework and she did. But when we got home I noticed something....and I looked at Anna and said to her "Anna didn't I buy you 4 books?!" she then looked at me with confusion on her face and said I thing so...:-/ why mommy?? omg don't mommy me there is only 3 books in your backpack!!! Then she said "oh no I think I left it in the library!!! We have to go back and get it! An like a good mother I am. We went back to the school. But the librarian had left for the day. So she then started to cry and I look at her asking,"why are you crying?!?" as she wiped her face she says to me "you said tomorrow the books are getting picked up mommy! What if my book gets put back!?!" :*( geeezzz well then I guess next time you'll listen to me and keep the in your backpack until we go home! Good Grief!! I pray we found her book! Cuz let me tell you buy books at the school book fair is not cheap!! Well tomorrow is going to be another crazy day. Anna has her first field trip to the farm, Kris has school, I also need to turn in Anna's cookie dough money but I still have two people to collect from. The things we do for our children...even when they do the things they do! Peace, Love and Good-night