Usually when someone asks this, they're asking about your feelings. In science, we're talking about everything around us. Since the concept of matter can be quite profound for a young scientist, we simplified out focus by incorporating experiments around the changing states of matter. For our first experiment, we learned how an item goes from a solid to a liquid. We then moves on to explore how liquids can become a solid. Lastly, we made Moon Sand to explore semi-solids (see recipe below).
Moon Sand Recipe
3 cups of play sand
1 1/2 cups constarch
1/4 to 1 cup cold water
Mix ingredients well by hand. Add water until you have a substance that can hold its shape for a few seconds, but then starts to melt after it warms up in your hand. To store, place in a zipper bag and add water prior to playing with it again.