Video narration
What in this room is matter-and what isn't? The chair and the water in a glass are matter. But is the air matter too? And what about light coming through the window? Matter is anything with mass that takes up space. Mass means how much material something has; taking up space means it occupies room, even when you can't see it. A chair is a solid: it keeps its shape. Water is a liquid: it flows and takes the shape of its container. Air is a gas, spreading through the room. Here's the surprising part: invisible does not mean non-matter. Air has mass and occupies space. Light is different. It carries energy, but it does not have mass or take up space like matter does. So, what in this room is matter? You, the chair, the water, and the air. Light isn't matter.