My granddaughter just turned 9 and is the same way. She's all into carrying the things she's come to think are important to take into the parks. She carries a small soft vinyl backpack. It's water resistant so that helps especially in the summer months but it fits her autograph book, a snacks, bottle of water if needed, her pressed penny book, and her change purse as well as whatever else she comes across. It could hold a lot more but I'm a minimalist when it comes to doing the parks so I encourage her to keep it simple. She carries it all day except when we get onto rides. I want to make sure it's stored appropriately etc...but she's known from the first moment I will not carry it. I'm not one of those people who says sure bring the kitchen sink because the grown ups will carry it for you...not gonna happen. We've both done the pack thing from time to time depending on the circumstances and I find it can be handy since it leaves a child hands free. We took a soft material zipper top sort of like a make up bag I got off a sales rack at target and added a strap that she wears as a pack at times. It's a manageable size and the soft material lies flat so it's not a big bulky thing like so many packs are.
