I also like this simple exercise, a spin-off from an activity described on the USGS site above.
Take students on a neighborhood walk and see what you can observe about age dates around you.
Here is an easy-to understand analogy for your students: relative age dating is like saying that your grandfather is older than you.
You might have noticed that many of the oldest age dates come from a mineral called zircon.
Here, using the Rhenish shield (western Europe), an area of moderate Quaternary uplift, as a test case, I attempt to build an index yielding a comprehensive view of the stage attained by the landscape's response and, indirectly, an evaluation of the timing of the triggering base level change.
This index, called , is a ratio of differences between the three integrals linked respectively to the classical basin's hypsometric curve, to the main river's long profile, and at the intermediate level, to a ‘drainage network's hypsometric curve’.
The narrower a range of time that an animal lived, the better it is as an index of a specific time.
No bones about it, fossils are important age markers.