Today we introduced one of my favorite topics: chemical reactions. We defined a chemical reaction as “does change the chemical formula; creates a new substance.” We also discussed how, because you can’t actually see the atoms, it can be hard to distinguish between a chemical reaction and a basic physical change. So I taught them to look for four clues: color change, temperature change, bubbling, and glowing. If you see more than one of these four clues, there’s a good chance you’re looking at a chemical reaction.
After this discussion, students completed a worksheet (posted below) where they tried to classify changes as physical or chemical. At the end of class, we corrected their work.