Pot-in-Pot Lab: lesson plan
Jaime Toney & Shawna Hollen, October 14, 2008
Order of the lesson: It may be best to get the kids to build the pots at the very
beginning of the lesson, without introduction, so that they can take data throughout
the class time. The background information can be taught once the class is waiting
for the pots to cool. Then the kids can use the rest of the class to record data and
arrange the lab in their science notebooks.
Brief introduction to pot-in-pot: The pot-in-pot refrigerator uses evaporative
cooling to keep an inner pot cooler than the outside air temperature. It works best
in a hot, dry climate, but the results are noticeable in normal room and humidity
conditions. A Rolex Award was given to Mohammed Bah Abba of Northern Nigeria
for the design that is now used to keep produce fresh in some parts of Africa,
especially open markets. (Pictures in power point file.) In addition to teaching
students about energy and heat transfer, this lab could be used to motivate a
discussion about the convenience of appliances in our lives, how people did (and
still do) without these appliances
Background:
 All matter is composed of small particles called atoms. Matter can be in three
forms: solid, liquid and gas. In all of these forms, the particles are always in
motion, so they have energy.
 How fast the particles move is different in solids vs. liquids vs. gases (have
students guess in which they move fast/slow). The motion of particles is
what we measure as Temperature.
 Energy that flows from an area of high temperature to low temperature is
called Heat.
 There are three ways that we can heat something:
1. Conduction
2. Convection
3. Radiation
 Use three methods of cooking popcorn as an analogy:
1. Oil in the bottom of a pan. Cover the bottom of the pan with popcorn
kernels. Place the pan on the stove and turn on the burner to medium
heat. Cover the pan with a lid. Periodically shake the pan so the
kernels move around in the oil.
 Conduction: heat is transferred through matter – in this case
by direct contact from the metal pan to the oil and to the
kernels
2. Obtain a popcorn popper. Place the popcorn kernels in the popper.
Plug in/turn on the popper. Hot air will transfer heat to the kernels,
making them expand and pop.



 Convection: heat is transferred via mass moving from one
place to another – in this case the hot air transfers head to the
kernels until they pop.
3. Microwave a bag of microwave popcorn.
 Radiation: heat is transferred through relatively empty
space – in this case radiation in microwaves radiates heat to
the kernels, which in turn radiate heat to other nearby kernels.
Can use the heat transfer worksheet here to check for understanding.
(Optional emphasis) Glass of ice water, glass of hot water:
1. From beginning of lesson have a glass of ice water and a glass of hot
water sitting on the counter where the kids will notice them (could
also just use one or the other).
2. After explaining the different kinds of heat transfer, ask what will
happen to the two glasses of water over time.
3. Ask them to use what they learned about heat transfer to describe
how the heat leaves the hot water to cool it down, and also how heat
from the room enters the cold water to warm it up. (Conduction
between glasses and tabletop, water and glass. Convection: water
mixes as it cools, warms – best example: ice in the cold water glass
melts, cold water at the top of the glass then sinks to the bottom.
Radiation: what would happen if we put both (or one or the other)
glasses in the sun?)
Evaporation: requires energy to go from liquid to gas…example sweat.
Discuss movement of particles and removal of heat.
Objectives: Students will understand why evaporation causes cooling and
distinguish among heat transfer via conduction, convection and radiation.
Materials for each Group:
 Two clay pots, one larger than the other
 Sand
 Water
 Cloth to cover pots
 Clay, cork or other material to plug holes in pots if they have them
 Thermometer (preferably reads from tip)
 Masking tape to hold thermometer in place
 Funnel
 Gallon jugs of water
 Sand holder for each group
 Graph paper
Science Notebooks:
 #, Name, Date
 Title – Pot-in-Pot Lab







Hypothesis Question: What will happen to the temperature inside the little
pot as water evaporates from the sand?
Materials:
o Two clay pots
o Sand
o Water
o Cloth
o Clay
o Thermometer
o Masking tape
o Funnel
Procedure for them to glue:
1. Plug the holes in your pots with clay.
2. Pour sand into the larger pot. Use enough sand so when you put the
smaller pot into the larger pot, the tops are even.
3. Fill the space between the pots with sand.
4. Pour water on the sand until the sand can absorb no more.
5. Dampen your cloth and cover the inner pot.
6. Push your thermometer through the tape patch in your cloth.
7. Record the time that you put the thermometer into the pot.
8. Measure and record the temperature inside and outside your pot every
few minutes.
Data table to glue in notebook.
Graph paper to glue in notebook.
Conclusion:
o What happened to the temperature inside your pot? Why?
Example discussion questions:
o Will the pot eventually dry out? Why?
o Where does the water go?
o Draw a picture showing what happens to the heat inside your pot.
Where does it go? How is it transferred (how does it get there)?
Background material and popcorn analogy from:
http://outreach.physics.utah.edu/labs/atmosphere/popcorn.html
Pot in Pot instructions found at:
http://www.seed.slb.com/en/scictr/lab/pot_refrigerator/index.htm
Rolex award for design (2000):
http://rolexawards.com/en/the-laureates/mohammedbahabba-the-project.jsp