STEM FAIR PROJECT
Project title: DIRTY PENNY CLEAN
Student Name: Jacob Aryee
STATEMENT OF THE PROBLEM
• Which solution will clean a dirty penny better?
RESEARCH
• Pennies:
– 30 million pennies are produced each day!
– A picture of the Lincoln Memorial is on the back of the penny (since 1959)
– Pennies are produced at the US Mint in Philadelphia (GO EAGLES!!!) and Denver
– If former President Lincoln were alive today, he would be 202 years old
VARIABLES
• Controlled variables: Amount of liquid (1 cup), size of container
(plastic cup), length of time in liquid (5 minutes)
• Independent variable: Cleaning Solution (e.g. cleaning agent added to
water)
• Dependent variable: The cleanliness of the penny
HYPOTHESIS
• I predict that the pennies will clean better with the laundry detergent
and water because the buttons on my jackets, jeans and shorts are
always clean after my mommy washes them in the washing machine.
I believe the buttons on my jackets, jeans and shorts are made of the
same metal as a penny.
MATERIALS
• 3 dirty pennies
• 3 plastic cups
• Water
• A teaspoon
• Arm & Hammer Free & Clear laundry detergent
• White vinegar
• Salt
• Arm & Hammer baking soda
PROCEDURE
• Collect 3 dirty pennies
• Place dirty penny in cups A, B and C
• Pour 1 cup of water into plastic cup A
• Pour 1 teaspoon of laundry detergent into cup A and stir
• Pour 1 cup of water into plastic cup B
• Pour 1 teaspoon of baking soda into cup B and stir
• Pour 1 cup of white vinegar into cup C
• Pour a teaspoon of salt into cup C and stir
• Allow each penny to soak in the solution in each cup for 5 minutes
• Remove pennies from each cup carefully and inspect cleanliness of pennies
• Record Data
DATA/OBSERVATIONS
Dirty Penny Turned Clean Experiment Results
Effectivness
1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Series1
0.25
0
Detergent/Water
0.25
Baking Soda/Water
0
Experiment Descriptions
Vinegar/Water
1
• Note: To measure, we decided to come up with our own scale to show the effectiveness (how well)
of the solutions. 1 is the highest and simply means the solutions did in fact clean a good portion
of the penny. 0 indicates that the solution did not alter the appearance of the penny.
CONCLUSION
• The results indicated that vinegar and salt was the best cleaning
solution for cleaning a dirty penny. I thought that detergent would
work since it cleans my dirty clothes and my buttons are always clean
after washing. But detergent didn’t really make the penny very clean.
With the salt and vinegar solution, 1 side of the penny became really
shiny. The other side got shinier too, but it also developed a black
mark which was strange.
DETERGENT
Water!
Detergent!
DETERGENT RESULTS
BEFORE
AFTER
Not bad. But
let’s see if we
can get it
cleaner!
BAKING SODA
Baking Soda!
Mixing!
BAKING SODA RESULTS
BEFORE
AFTER
WONK
WONK
WONK 
An epic fail!
VINEGAR & SALT
Salt!
Vinegar!
VINEGAR & SALT RESULTS
BEFORE
AFTER
Look
at that
shine!
WORKS CITED
• Interesting Egg Fact. http://didyouknow.org/eggs/