Radioactive Decay Demonstration
Article Author:
Summary of Activity:

Play a game to understand how radioactive decay works!

Estimated Prep Time:
Estimated Activity Time:
Estimated Total Hours:
  • Nuclear 101
Target Audience:
  • General Public
  • Primary School Students
  • Secondary School Students
  • University Students
Submission Type:
Ready-To-Go Event
Activity Type:
Activity or Demonstration
Detailed Description and Instructions:


  • Tables with standing room for each participant

Supplies: (i.e., paper, pencils, markers)

Expo/Booth/5th grade and younger

  • One bag per participant with 15-45 M&Ms (or wrapped candies with clear markings on 2 sides (we used mints with U.S. WIN logo printed on one side, could use pennies)  if doing at a booth/expo where the candies will not be handed out)
  • If doing at an expo, box tops to mark spots (tops of computer boxes work well)

6th Grade and older

  • Graph paper
  • Stop watch

Equipment: (i.e., laptop, projector, whiteboard)

  • Handouts if doing full radioactive decay module for 6th grade or older

Event Preparation: (i.e., group meeting(s), dry run)

  • Contact group leader/teacher to ensure no food allergies with M&Ms/snacks provided

Activity for Booth/Expo and 5th Grade or younger

Background on Activity

  • Nuclear Power plants use radioactive materials to produce power
  • Radioactivity is when a material gives off part of its energy. 
  • Half life is the time for half of the materials energy to be given away (for the adults, half life is how long it takes for half of the atoms of a radioactive substance to decay into another isotope)
  • The half life of different materials can range from less than a second to millions of years

Give instructions and then do a demonstration

To demonstrate radioactive decay

  • The mints are a radioactive material that decays with time. 
  • Drop the mints on the table
  • Remove the mints that have writing showing to represent the radioactive material decaying away
  • Repeat until there are no mints left

After the activity is done:

  • Radioactive materials are used in nuclear power plants to produce fuel
  • Scientists use the half life of carbon to determine the age of fossils.
  • Scientist use radioactive materials to take x-rays and treat cancer patients.
  • Radioactive material exist naturally in the world
  • Radioactive decay is a normal part of life.

Lessons Learned:

  • Ensure you know how to frame the radioactive decay activity using real life examples where radioactive decay occurs, especially for the expo/booth activity where you have less time.
  • Ensure you have enough extra handout sheets in case someone needs an extra.
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