I am a solid. My name is Cube! I have straight sides, flat surfaces, and I don’t change shape. You can touch me and I will stay the same. I live in the world of solids where my friends like Ball, Box, and Book also belong.One day, Water and Air came to play. They kept changing shape and flowing everywhere. I couldn’t do that, but that’s okay! I’m strong, I can be stacked, and I help build houses and toys.Even though we’re different, we’re all important in the world of matter!