Air is classified as matter because it consists of a collection of particles that have mass and take up space. Matter, by definition, is anything that has mass and occupies volume. Even though we cannot see air directly, it is made up of tiny particles such as oxygen, nitrogen, carbon dioxide, and other gases. These particles are constantly in motion and interact with one another, which is characteristic of matter.
When we consider air, we can notice its effect on the environment around us. For instance, when the wind blows, we can feel the movement of air against our skin, and we also observe that air can exert pressure (for example, when we inflate a balloon). This pressure is a result of the air molecules colliding with the surfaces around them, confirming that air is indeed a physical substance.
Additionally, air can support combustion and is essential for breathing, which further illustrates its properties as matter. Therefore, despite being invisible, air meets the criteria for classification as matter due to its composition, volume, and mass.