Radioactive dating lab pennies
" After introducing some of the concepts involved in radioactive decay, I do the demonstration. Tell them that they will be flipping the penny (you will tell them when); each time they flip one half life will have passed.
I usually let them keep the penny at the end of the class. If their penny lands on heads, they are radioactive and have decayed and they should sit; if their penny lands on tails, they have not decayed and may remain standing.
Students should begin to see the pattern that each time they “take a half-life,” about half of the surrogate radioactive material becomes stable.
Students then should be able to see the connection between the M&M’s and Puzzle Pieces and radioactive elements in archaeological samples.
The piles graphically show the meaning of the term “half-life.” Toss all the pennies onto a table surface.
The chance that any penny will come up tails on any toss is always the same, 50 percent.
However, once a penny has come up tails, it is removed.
The demonstration usually takes approximately 5-10 minutes depending on how long it takes to count the students.
If your class is particularly large, you might want to have a few students help you count the "undecayed" isotopes.