This is another versatile demonstration to use in your student of chemistry - learn about chemical changes, chemical reactions, conservation of matter and even air pressure. Depending upon the take-home message you want your students to get, you might structure the activity in a few different ways, but the basics are the same. You'll need some steel wool, vinegar, bottles or flasks and a balloon. Pull apart some strands of steel wool and push some into each bottle. Pour some vinegar onto the…