I did this experiment with my 7 year olds . The idea is that the acid in many things will make a non-shiny penny shiny . I had my kids guess which would work the best .
What you need : some “ dull ” pennies dish soap vinegar lemon juice , salsa or anything else that is acidic water
small cups ( I used plastic cups we use for mouthwash )
The experiment : First I asked my kids to guess which would work the best - they wrote their answers on index cards . ( side note : I find it hilarious that my daughter insists on always writing her last name ) Next , we filled the cups with ( 1 ) soapy water , ( 2 ) vinegar , ( 3 ) salsa , and ( 4 ) lemon juice . We then put a penny in each cup and waited for one minute . Result : After a minute - the vinegar penny was the shiniest
For the fun of it , we decided to put the pennies back in and see what they looked like after an hour and the result changed to the lemon juice penny !