Radioactive-Decay Model: Substitute coins for radiation

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Get a roll of pennies, throw them on the ground, then remove those that only show tails, and repeat with the ones left over. In this Exploratorium Science Snack, this is how you create a model of radiation decay.

Quick Guide

Preparation Time:
Under 5 minutes

Learning Time:
5 to 10 minutes

Estimated Materials Cost:
free per student

Age Range:
Ages 8 - 18

Resource Type:


Materials List (per student)

  • At least 100 pennies
  • A container to hold the pennies
  • Optional: 100 small wooden cubes approximately 2/5 inch (1 cm) on a side, with one side painted red


  • Mathematics
    • Data Analysis and Probability
    • Measurement
      • Rate
  • Physical Sciences
    • Structure and Properties of Matter
      • Atomic Structure
      • Elementary Particles and Nuclear Physics
      • Mass and Weight
  • The Nature of Science
    • The Scientific Process
      • Gathering Data


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Access Rights:

  • Free access