How can you simulate radioactive half-life?

1 Answer
Mar 17, 2014

Use pennies to simulate unstable isotopes. When the pennies are heads up, they are radioactive (unstable). When the pennies are tails up, they have decayed to become stable isotopes.


  1. For “Event 0”, put 100 pennies in a large plastic or cardboard container.

  2. For “Event 1”, shake the container 10 times. This represents a radioactive decay event.

  3. Open the lid. Remove all the pennies that have turned up tails. Record the number removed.

  4. Record the number of radioactive pennies remaining.

  5. For “Event 2”, replace the lid and repeat steps 2 to 4.

  6. Repeat for Events 3, 4, 5 … until no pennies remain in the container.


Repeat Trial 1, starting anew with 100 pennies.

Calculate for each event the average number of radioactive pennies that remain after shaking.

Plot the average number of radioactive pennies after shaking vs. the Event Number. Start with Event 0, when all the pennies are radioactive. Estimate the half-life — the number of events required for half of the pennies to decay.

You can find a worksheet for this simulation at