"Whats Dissolve?"

Sometimes its just easier to show an answer to a question, so when Claire asked me, 'Whats dissolve?' I told her to get some salt, sugar and a couple cups of water. She went the extra mile and got powdered sugar as well as the regular granulated stuff. Then she poured and stirred and observed. Finally she defined dissolve as 'when something disappears into water'. I don't know why I was having such a difficult time trying to define it for her!