The experiment began with observations of the liquids and powders. We recorded the color, texture and smell of the different substances, describing their properties. Then the mixing began.
The question - "Which combination of substances results in a chemical change?"
Nothing happens when you add salt to water or salt to vinegar. Nothing happens when you add baking soda to vinegar. It wasn't until they comined the baking soda and vinegar that things got exciting.
"How do you know it's a chemical reaction?" I asked. Most of the kids explained that you couldn't undo the combination and get the powder back. Although I see their reasoning - I wanted them to focus on how the chemical reaction creats a new substance - the gas bubbles.
We will keep working on it. Next up, Chromatography and Invisible Ink.