Exploring the states of matter was an activity very close to my heart. Being a chemist I am very familiar with particle theory, so it was fun to have the whole class moving as particles and then to create our own sequences of phase changes. One change I would make to the activity, however, would be to remove plasma from the discussed states! Perhaps this is my background speaking, but plasma is generally ignored as a state of matter here on Earth, and it only serves to confuse students about its relationship with the other states. Moving from solid to liquid to gas seems somewhat intuitive as particles become more energetic and spaced out. But changing from gas to plasma when ionized? What is ionization? That's not part of the grade seven curriculum! But I digress. I liked this activity because it focused not only on one's own energy, but on the energy and relationship between all members of the group. Students could demonstrate the very energetic particles of a solid through small, quick movements while standing close to one another, then begin to drift apart and increase their use of space to demonstrate liquids and gases. Linking the changes to one's body makes the underlying properties and theory much more intuitive, and I look forward to trying this in my own classroom sometime.
