Understanding Half Life
This activity is a demonstration of half‐life, and why the age of fossils are estimates based on half‐lives.
Materials:
- 100 m&ms (you may need around 7 to 8 packs)
- 1 round container with a lid
- 1 large sheet of baking parchment paper
- 1 bowl
Instructions:
1. Count out 100 m&ms and lay them down on your baking parchment paper with the 'm' side facing down. This shows you the beginning of the substance's decay cycle.
2. Carefully pour all 100 m&ms into the round container and place the lid on it. Roll the container around for a few seconds, or shake the container for a few seconds. This symbolizes one half‐life.
3. Pour the m&ms out of the container and back onto the baking parchment paper. Make sure each m&m is lying flat on itself.
4. Remove all the m&ms with the 'm' side facing up and place these in a bowl. As you remove them, count the m&ms. How many did you count out? How many are left? Record these numbers.
5. Repeat the procedure of placing the m&ms that remain on the parchment ('m' side down) and shake them in the container.
6. Keep counting out the m&ms that come back 'm' side up and recording the numbers that were removed and the numbers that got left behind each time. Do this until you have no candy left.
You should notice that each time a “half‐life” occurs, the number of m&ms counted out and the number of m&ms remaining are not exact halves of a whole. If this activity is repeated several times and the plotted on an average graph, you will notice a pattern and be able to estimate the m&m half‐life. However, when scientists determine half‐lives, they have calculations that can give them more or less the exact times that would give them exact halves of the whole.
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