Why is this the answer?

The answer is pencil because this clever riddle uses fun word pictures to describe one of the most important tools you use every day in school and at home. A pencil is the perfect match for all three clues, and it is an object you probably hold in your hand right now as you read. First, let's look at the first line of the puzzle, "I usually wear a yellow coat." When you think about a brand new pencil, you'll see that it is covered in bright, cheerful yellow paint. This paint is like a warm, protective coat for the pencil, keeping the soft wood and the tiny graphite core safe inside. The famous yellow color is a popular choice for pencils all around the world, which is a great hint that we are talking about a common school supply that helps you learn. The second clue talks about a "dark head." This part of the riddle is pointing right to the sharp tip of the pencil. After you use a sharpener, the wood peels away, and you can see the small, dark piece of graphite that is used for writing. This dark graphite is the pencil's "head," ready to think up and write down all your amazing ideas. The contrast between the dark graphite and the bright yellow body makes this "head" stand out very clearly. Finally, the riddle says, "I make marks wherever I go." This is the whole reason we use a pencil! As you move it across a piece of paper, the dark graphite leaves a perfect, traceable mark. Whether you are writing a story, working on a spelling test, or drawing a picture of your pet, the pencil is always there to leave its mark. It helps you keep track of your thoughts and turn them into something you can see and share with others. It is an essential tool for all your learning adventures. Because it has a colorful coat, a dark writing head, and leaves marks everywhere, the pencil is the perfect solution to this excellent riddle.