Title:
Penny Puddle
Designed by:
Loryn Doneson
Temple University: College of Education
Summary Purpose
of this Inquiry Lesson
• Surface tension allows a penny to hold more
drops of water than one may expect it would
hold.
Materials
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4 pennies (make sure each has a different date stamped on it)
Nickel
Dime
Quarter
Paper Towel
Eyedropper
Cup
Water
Pencil
Data table
Please print this data table sheet to
assist with data collection.
Step 1:
Gather all of the necessary materials you need to
complete this experiment.
Step 2:
What do you think will happen?
(Make predictions on the data table sheet)
How many drops of water do you think will fit on the
head of a…
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Penny?
Nickel?
Dime ?
Quarter?
Step 3:
Place a penny on the paper towel with the head facing
up.
Step 4:
Fill the eyedropper with water.
Step 5:
Hold the eyedropper close to the penny, and very slowly
squeeze drops of water on the coin.
Step 6:
Observe the shape of the mound of water.
Count the number of drops the penny will hold before
the water spills over the edge.
Step 7:
Repeat the activity with 3 other pennies.
*Make sure each one has a different year stamped on it.*
Step 8:
Repeat the activity with a nickel, a dime and a quarter.
Step 9:
Record how many drops of water each coin held and
graph your data.
Only graph the data of the pennies!
Student Sample: Data Table
Coin
Penny (year: 1937)
Penny (year: 1960)
Penny (year: 1989)
Penny (year: 2007)
Nickel
Dime
Quarter
Drops of Water
23
26
31
35
40
24
43
Student Sample: Chart of the Data
What was happening?
• Water molecules are attracted to themselves
more than they are to the surface of the penny.
This causes the water mounds to form a curved
surface on the top of the penny. This is called
surface tension.
• The number of drops of water a coin can hold is
affected by several factors including the size and
the age of the coin. This was shown by seeing
how many drops of water fit on a nickel, a dime
and a quarter.
What was happening?
• In general, older coins have been in circulation
longer and have worn edges.
• Newer coins have higher edges that are able
to hold more water.
• Since height is a factor, you may find a smaller
coin holds more than a larger coin.
• Water has the highest surface tension of any
liquid and you should be able to fit more
drops of water on any coin.
Variations of Experiment
• Adding a few drops of detergent in the water.
Detergent decreases the surface tension.
• Try nickels, dimes or quarters that were made
during different years.
• Adding salt to the water.
Links to Internet Resources for this
Inquiry Picture Lesson:
• http://www.ise514.org.uk/prim3/new_guidelines/newsletters/
39/Surface_tension.htm
• http://www.exploratorium.edu/ronh/bubbles/
sticky_water.html
• http://pbskids.org/zoom/activities/sci/pennies
andwater.html
• http://www.sciencebob.com/experiments/pap
erclip.php
To see other picture lessons go to…
http://science-inquiry.wikispaces.com/