How many of us struggle with explaining integers? I know that I do. I find it most difficult to teach topics that are completely obvious to me, that I don't remember ever learning. So integers are right up there. Many years ago my friend, Tom Seidenberg, told me that he used the idea of a hot air balloon and sand bags. I ran with that and have been using it ever since. I am by no means saying that this is the best way to teach integers, but it does give students something concrete to hang on to. I must also say that my students have already been taught about integers, but many did not understand them the first time. This gives students a different way of thinking about integers. It takes a lot more than this to get them comfortable working with integers, but this is how I start.