Why is this the answer?

The answer is smoke because this clever riddle uses fun word pictures to describe something that is everywhere but impossible to hold in your hands. Imagine you are watching a cozy campfire or a warm fireplace. This puzzle tells the secret story of what smoke does. The riddle's first part gives us three big clues about where this mystery thing can go: "A house full, a yard full, a chimney full." When wood or coal burns, the smoke that comes out does not stay neatly in one little spot. First, it rushes right up the chimney, easily making the chimney full. But smoke does not stop there. If the wind is blowing outside, the smoke can drift and spread across the whole yard. And if a fire is inside, the smoke will quickly fill every single room. The riddle is trying to show you that smoke is very good at filling up large spaces very quickly, whether it is an inside space like a house or an outside space like a yard. The last clue is the most important one and it is designed to trick your brain: "no one can get a spoonful." You can easily pick up a spoonful of soup, water, or even sugar because those things are solid or liquid. But smoke is not like that. It is made up of tiny little dust particles and gas floating in the air. Even if you try your very hardest to scoop it up with a giant ladle or a small spoon, it will just slip right through and disappear. You can definitely see smoke, and you can smell it, but you simply cannot grab it or hold it. Because smoke can fill everything but cannot be caught, it is the perfect and only answer for this wonderful word puzzle.