I think I will use part of the Evidence of Plate Tectonics EET Chapter (http://serc.carleton.edu/eet/evidence/index.html) , but just focus on the seafloor age section. The data used in this activity is already bundled with the ArcVoyager program.

I might have the students complete this activity first and then ask them to explain the data: how the seafloor could be made of rocks that are different ages.