Day 121: Radiometric Dating


Students in IS II used index cards to model the radioactive decay of Carbon-14 to stable Nitrogen-14. Keeping track of the increasing daughter isotopes and the decreasing parent isotope allowed them to see how the ratio of C:N relates to half-life and to absolute age. The index card helps them understand the limits of C-14 and other radiometric decay series.


We then got out the “cubium” atoms (wooden cubes with one side shaded). Each shake of the box represents the passing of time equal to one half-life of cubium. We have all seen this done with M&Ms and pennies but the twist here is that the decay is not a simple 1/2, 1/4, 1/8, etc. Students will conduct three full decay trials, graph the results, and interpret both the data and the graphs.


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