Teaching Radiioactive

Teaching Radioactive Decay:

Radioactive Half-Life and Dating Techniques

Daniel Gray

Target age or ability group: | This activity has proven effective for high school biology students of all ability groups. (Some lower level students need help with the math but they can understand the concept properly.) |

Class time required: | The activity takes about an hour of student work plus discussion time. The follow-up activity takes twenty minutes to half an hour. |

Overview of activity: | Students generate a radioactive decay table for an imaginary element (designed to simplify the math), use their data to plot a decay graph, develop the concept of half-life, and use the graph to "age" several samples. The follow-up exercise tests students' understanding by having them generate a C14 decay graph and use it to date a post-ice age murder. |

Teacher instructions: | My students are familiar with simulations introducing complicated subject matter. They know that they will be expected to apply a simplified model like this one to a more complex situation in a follow-up exercise. You will get a better response from students not familiar with this learning technique if you explain what you are doing before you start. For each group you will need to provide a container with 900 pinto beans and 100 M&M's to simulate the 1 to 10 ratio of radioactive isotope to stable isotope. There must be exactly 100 M&M's for this exercise to work correctly. You don't need exactly 900 beans; the students never count them. I find the mass of 100 beans and use it to estimate 900 beans. The class will need six bags of "radioactive atoms" (between 5 and 100 M&M's in a bag). These bags represent the remains of various people/ organisms. A bag contains only the radioactive portion of the sample that was found along with 900 stable atoms. |

Teacher Guide: Radioactive Decay Simulation

Scenario I use to start this activity. (redesign to match your situation). The recent...