Home by ourselves and I want to bond?

me and my sister are at home by our selves and its like SUPER hot outside. I want to spend more time together but im 13 and shes 15 so she doesn't want to spend time with her stupid younger sister unless shes watching tv in the living room and I sit quietly watching r on the computer. I want to do something fun but we cant leave the house and like I said its super hot but we don't have air conditioning in our house besides our play room (finished attic) that we haven't used for years. Even if we did go up there to stay cool what would we do? there's no computer and no tv, just a small chalk board ripped stuffed animals and our brothers old lego sets. What can we do?