5th Grade Science Standard 1 Objective 2 "Evaluate evidence that indicates a physical change has occurred."

Use several household products to turn a dirty penny into a clean, shiny penny.
UEN Penny Lesson Plan

Make predictions about how well a household product will clean a dirty penny. Fun graphics to explore your prediction without actually doing the experiment.
Cleaning Pennies (baking soda, vinegar, lava soap, lemon juice)

Learn how money is made and explore why the copper of pennies reacts with household products, specifically acids.
How is Money Made?