Remember carbon-14 dating cannot be used to date most fossils.For more information on the restrictions on carbon-14 use in fossil dating see the carbon-14 background information page. Explain that each student will represent one carbon-14 atom in the artifact.You could have 1 trial = 10,000 years, for example.Then students can determine the half-life of the class carbon-14 in years. You may wish to repeat the class sampling again near the end of the hour to see what differences exist between the two smaplings.Students would then be assigned to determine which element they had based on the decay plot they recieved.
Another great half-life activity is available through Resources for Educators.Discuss the method of averaging many trials with your class as a way of obtaining a more accurate result.This activity seeks to teach students the concept of half-life and radioisotope decay.Make sure to be clear that the carbon-14 atoms in this artifact represent only a small percentage of all the atoms that compose it. If the penny is heads the student decays to carbon-12 and must sit down.Remind students that the majority of the artifact will be made up of carbon-12 or other atoms. If the penny comes up tails the student remains undecayed and may remain standing.Student plots should show a half-life decay pattern as in the plots below: In the plot above, the number of remaining undecayed atoms has been converted to a mass, and the trial number has been converted to years.The same pattern of decay should be visible in your class data. When students have created their plots discuss the results as a class.Students will learn the concept of half-life, be able to identify the half-life of an isotope from a plot of its decay, and understand the potential application of the concept of half-life in the dating of biological and geological artifacts.Teachers may wish to seek additional background on carbon-14 or half-life before beginning this activity.To test student understanding teachers may wish to use a short quiz. Teachers may also wish to use a more interactive assessment model.A more interactive assessment could include having each student invent an isotope.