Pot-in-Pot Refrigeration

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In this activity (on page 2 of PDF), learners create a low-tech refrigerator that requires no electricity to keep food from spoiling. It uses only clay pots, one smaller than the other and separated by wet sand. As the water evaporates from the sand, it lowers the temperature inside the inner pot, similar to how evaporation from a sweaty person lowers the person's body temperature. This "refrigerator" with no moving parts is great for exploring evaporative cooling, as well as scientific innovation, especially since it has been used successfully in Africa. [Activity is publicly available through a web crawler capture on Archive.org.]

Quick Guide

Preparation Time:
5 to 10 minutes

Learning Time:
1 to 2 hours

Estimated Materials Cost:
$1 - $5 per student

Age Range:
Ages 8 - 18

Resource Type:


Materials List (per student)

  • 3 clay pots, one slightly larger than the other
  • sand
  • 2 pieces of Cloth (to cover the pots)
  • water (room temperature)
  • 2 small containers with lids that can fit in the small pot (baby food jars work well for small pots)
  • small piece of cardboard


  • Engineering and Technology
    • Technology
      • Agriculture and Biotechnology
  • Physical Sciences
    • Heat and Thermodynamics
      • Heat and Temperature
      • Heat Transfer
      • Thermodynamics and Entropy
    • States of Matter
      • Liquids
      • Gases
      • Changes of Phase
  • The Nature of Technology
    • Technology and Society
      • Impacts of Technology

Informal Categories

  • Outdoor Activity


To use this activity, learners need to:

  • touch

Learning styles supported:

  • Uses STEM to solve real-world problems
  • Involves hands-on or lab activities


Includes alignment to state and/or national standards:

Access Rights:

  • Free access



Funding Source:

  • National Science Foundation, ESI-0206403