Suppose you made some beef soup. you want to separate the extra fat from the soup before you eat it. how could you do that?

Fat from beef is actually a non saturated fat. Non saturated are somewhat solid in form at room temperature. So to separate the extra fat from the soup, what we could do is to put a cold water in a plastic, then ran over that plastic into the soup. The result in this would actually fat sticking on the plastic.