Representing the three main states of matter from simple materials offers you a deeper understanding of the structure of the stuff you see all around you. Styrofoam is perfectly suited to replicating the structure of liquids, solids and gases because it can be bought in balls, each of which can represent an atom or molecule. Using this simple property allows you to create a basic representation of the atomic structure of each type of matter.
Arrange some of your Styrofoam balls in a regular pattern, sticking them to one another using glue. Make a cube out of Styrofoam balls for a simple model of a solid. Use a lattice, criss-crossing pattern if you want to represent a metallic arrangement of atoms. You can make the structure several balls high to further convey the arrangement. This represents a solid, because the atoms are held together in a rigid alignment and can’t move around freely. In an actual solid, the individual atoms can actually vibrate in their positions, but this is extremely difficult to accurately represent using Styrofoam.
Choose a box for your model of a liquid. Making a liquid model is much easier because you can simply place several Styrofoam balls into the bottom of the box with no sense of order. Cover the bottom of the box with balls, adding more to create disorganised slurry of Styrofoam around two to three balls high. Liquids take the shape of their container, but the atoms don’t stay in a fixed position in the same way as in a solid. Tilt the box so that the balls move around, jostling past one another closely. This is how atoms and molecules move past one another in a liquid structure. Stick your hand into the box, noting that the balls change position to accommodate it. Demonstrate the difference by attempting to stick your hand into the solid model; the block will move to the side or break without letting your hand in.
Place less than one layer of Styrofoam balls into the bottom of the other box. Gases are a little bit like liquids, except they can move much more freely and aren’t in constant contact. This means that they can be accurately represented with a sparse arrangement of Styrofoam balls. Shake the box to demonstrate the motion of atoms and molecules in a gas. Gases spread out to fill their containers, and the atoms or molecules can react when they collide with each other. You’ll notice the balls thumping against the side of the box when you shake it. In a real container of gas, this creates pressure. If more atoms or molecules are in the container, more smash against the side and give it a higher pressure.