Get your students out of their desks and moving, acting like molecules in the different states.
Solid: students are clustered together, minimal movement
Liquid: students move a bit away from each other, but still close enough to reach out and maintain contact, slow walking and arm movements
Gas: students break away from each other and try to spread out as far as they can, walking and moving their arms at a rapid pace
*Try playing a game of Simon Says using these movements
*Try to find music to match each state of matter
*Have students write a story about what it's like to be a molecule that spends time in each state