Believe it or not, hospitals and the doctors that worked in them weren't always clean. In fact, doctors and surgeons didn't usually wash their hands between appointments. Gross, right? It wasn't until Joseph Lister came along that people found out just how important the simple act of washing your hands was to well-being. So the next time your parents tell you to wash up before dinner, read this worksheet and know they're not saying it for their own health. They're saying it for yours!