Activity Overview
Students examine actual radioactive decay data collected in an honors chemistry class to find an equation which best fits the data and allows a person to predict the count after certain periods of time have elapsed. Students review all their properties of logarithms by doing semi-log and log-log re-expression of data. An answer key with the answers worked out, is included.
Before the Activity
The instructor should have gone over semi-log (to get an exponential model) and log-log (to get a power function), re-expression of data with the class so students should be very familiar with the various log properties. The instructor should also download the two list files called "count" and "time", along with the two word files called "Radioactive decay activity" and "Radioactive decay answers." Copy Radioactive decay activity and distribute this to the class.
During the Activity
The instructor sends the lists, Time and Count to the class using the TI-Navigator™. The instructor then monitors the activity closely using TI-Navigator screen captures. The instructor could record credit when a team successfully has a scatterplot on a screen capture, for #1 and at other stages of this activity. Have students tell you when they think they have a good residual plot for #5 and again the instructor should record credit at that point. At the end of the activity, whole class screen captures can be used to decide which team has a model which fits through the data the best and discuss possible improvements in team results. See answer sheet included.
After the Activity
Instructor could use the TI-Data Editor™ in TI Connect™, or alter the data in the Edit menu of a calculator, to raise or lower the data and have the students do the same activity as an individual assessment. Pass out a copy of the answer key, attached to their labs.