animated video about plate tectonics. The videos does a nice job of explaining how the movement of tectonic plates is measured. The video also illustrate the forces that cause tectonic plates to move. The video is embedded below.
After your students watch the video above you might want to use one of the featured projects on the Google Earth educator's page about plate tectonics. The lesson was developed by Cheryl Davis for 5th and 6th grade students. The lesson uses Google Earth to help students understand plate boundaries and plate subduction.