Great Copper Cleaning Experiment

I enjoyed this easy experiment with my First graders that showed the amazing chemical change of a dirty copper penny(copper oxide) back into its pure clean copper. If you dip it into vinegar and a dash of salt you will see the change. You can also use lemon juice and tomato sauce. I thought it would be fun to experiment with other things that the kids came up with. We tried some cleaning items, soda, and spit. None worked as well as the things with acid.