Measuring Half-Life with a Simulated Radioactive Decay Model
A safer (and still fascinating) way to explore nuclear physics in the classroom.
☢️ What Is Half-Life?
The half-life of a radioactive substance is the time it takes for half the atoms in a sample to decay.
It’s a key concept in understanding radioactivity, nuclear medicine, archaeology (hello, carbon dating), and more.
But since bringing a pot of uranium into a school lab tends to cause… concern… we use simulations.
🎲 The Classic Classroom Simulation
A tried-and-tested method to model radioactive decay is using dice, coins, or counters to represent unstable atoms.
Here’s how it works:
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Give each student/group 300 coins (or paper squares, Lego bricks, etc).
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Each coin is an atom.
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Toss them all — every coin that lands “heads” has decayed.
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Remove decayed coins. Count the undecayed ones.
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Repeat the process for several “time intervals” (throws).
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Plot number of undecayed atoms vs. timE
Compare one set of results with the rest of the class - they will be remarkably similar.
Compare this to playing with 4 stud LEGO bricks, where the decayed particle is a LEGO brick the correct way up, a different rate but the same result.
📉 What You’ll See
You’ll get a lovely exponential decay curve.
It won’t be perfect (radioactive decay is random), but it illustrates the statistical nature of half-life beautifully.
You can even:
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Calculate an experimental half-life
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Compare different simulations with different starting numbers
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Discuss sources of error and real-life limitations
💡 Why It Works
This model helps students grasp:
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That decay is random for each nucleus
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That half-life is about probability, not a countdown
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That decay rates are measurable over time, even if individual events are unpredictable
🧠Extension Ideas
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Use multisided dice instead of coins (e.g., only 1s decay = longer half-life)
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Graph multiple runs and compare mean curves
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Link the activity to real-life isotopes like carbon-14 or iodine-131
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Use spreadsheets or PASCO sensors to enhance digital analysis
🔬 Final Thought
Understanding half-life doesn’t require radiation – just curiosity and some coins.
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