Simple facts about matter
Everything we see is made up of matter. All matter exists as solids, liquids, or gases. These are the three main states of matter. Substances can change from one state to another, like ice which can change from solid to liquid, or water that can change from liquid to gas.
Solids, liquids, and gases
Solid particles are tightly packed together with very strong bonds. They cannot move around freely and can only vibrate in a fixed position. Because they cannot move, solids have a fixed shape, they cannot flow or be compressed (squashed together). Their particles are arranged in a very fixed way.
Liquid particles are close together but not as much as solids, they are arranged in a random way. This lets the particles move around. The bonds between the particles are strong enough to stay together but not too strong that they cannot move. Liquids can flow and take the shape of their container but they cannot be compressed
Gas particles are far apart and arranged in a random way, there are no bonds between their particles which gives them freedom to move quickly in all directions. They can flow, fill their container, and be compressed.