Why is this the answer?

The answer is soap because this clever riddle uses fun word pictures to describe something you use every single day to get clean! A riddle is like a secret code, and we can look at each clue to solve the mystery of the thinning object. The first part of the riddle is, "You use it between your head and your toes." Think about when you take a shower or a bath. The soap is the perfect tool for washing your entire body. You use it right up on your head for washing your hair, and you use it down on your feet to wash your toes. You use it everywhere in between, which covers your arms, tummy, and legs. From the very top of you to the very bottom, the soap travels all over your body to do its important job of washing away germs and dirt. It is a simple object that helps us stay healthy every day. The second part of the riddle is the tricky one: "the more it works the thinner it grows." This is the best clue! What does it mean for soap to "work?" It means making bubbles and suds to wash away all the dirt, sweat, and germs. When you rub a bar of soap on your hands or a washcloth, the soap creates a foamy lather that cleans you. But every time you do this, a tiny little piece of the bar dissolves and washes away with the water down the drain. The more you use it to clean up, the more of the actual bar disappears. You can see this happen at home. If you compare a brand-new bar of soap to one that has been sitting by the sink for a few weeks, the new one is big, thick, and heavy. The old one, which has been "working" hard, is small, skinny, and much "thinner." It is a great example of an object that is used up by the job it is meant to do. This is a perfect description of a bar of soap. It helps you get clean from head to toe, and it gets smaller with every use until it is all gone. Great job being a riddle detective!