How we did it:
- dirty pennies
- vinegar (1 cup)
- salt (1 teaspoon)
- eye dropper
- jar with a lid
We started by filling a plastic jar with a lid with about a cup of white vinegar and about a teaspoon of salt.
Next, my daughter dropped in 5 very dirty pennies. She counted them as she dropped them in. :)
Then, I helped her put the lid on the jar tightly and instructed her to shake the jar pretty hard. In adult terms, pennies get dull over time because the copper in the pennies slowly reacts with air to form copper oxide. When you place pennies in a salt and vinegar solution, the acetic acid from the vinegar dissolves the copper oxide, leaving behind shiny, clean pennies! I explained that to my daughter in terms a 3 year old could understand. :)
Next, I held a strainer over a bowl and she poured the solution and the pennies out. She was excited to see them!
She examined them closely and said she wanted them "more shiny" so I gave her an idea dropper and she set to work dropping some more of the solution on the pennies.
After she was satisfied with how they looked, we gave them a quick bath in some cool water.
And voila! Brand new, shiny pennies!