# Understanding Radioactivity in Geology: The Basics of Decay

### This activity has benefited from a review and suggestion process as a part of an activity development workshop.

This activity has benefited from input from faculty educators beyond the author through a review and suggestion process as a part of an activity development workshop. Workshop participants were provided with a set of criteria against which they evaluated each others' activities. After the review, the authors developed a plan for revising their activities based on the feedback they received from their peers. To learn more about this review process, see http://serc.carleton.edu/quantskills/review_processes.html#2006.

This page first made public: Jul 23, 2006

#### Summary

One of a collection of PowerPoint/Excel modules designed to reinforce quantitative skills in geologic context. The module explores the exponential decay of radioactive parents through the analogy with popping popcorn. Students build a spreadsheet to calculate the number of unpopped kernels of popcorn as a function of time starting with the probability that a given kernel will pop during a 10-sec interval. The module introduces the mathematics of the exponential function as a modeling function in both analytical and numerical contexts.

## Learning Goals

- Consider a familiar occurrence of exponential decay in a quantitative way.
- Gain experience in forward modeling of an exponential decay phenomenon.
- Consider the relationship between the decay constant and the probability that a particular parent atom of a radioactive isotope will convert to its radiogenic daughter atom
- Gain experience in fitting a trendline to a column of data.