Here is a perfect activity to go with chapter 8. Unfortunately it seems like we skipped that one, but still here we go.
This site has a nice simulation to show the half life of radioactive elements, how they decay over time and how that can be used to date unknown samples. Goes really well with either a section on Geologic time scale or on the periodic table.
Included is a worksheet that I wrote for this one, feel free to use or modify if it might be useful.