Every year that I teach patriotic symbols, I always get the question "Why is it green?" Try this whole-group experiment to get to the bottom of this common student question.
I love this experiment because it takes very little prep and can be done over the course of several weeks without taking up much actual instructional time. My lab sheet is simple and student-friendly.
To conduct the experiment, simply place several pennies in a cup or bowl surrounded by paper towels. Saturate the paper towels in white vinegar and let sit, keeping the paper towel wet. Periodically pull out the pennies and do a "check up" on their progress. The more time you give them, the greener they will get!
Because this experiment is inquiry-based, do not give away the "why" until after students have finished the experiment!
Fun facts: Did you know that the Statue of Liberty contains enough copper to make over 30 million pennies? She is also built to withstand a hurricane despite her exterior only having the thickness of about two pennies :)