Here is a site with some nice animated GIFs. Downloaded and viewed in Preview, the cells can be viewed one at a time. If you look at the one that traces time backwards, the southern half of Alaska breaks off, drifts south, and appears to join Central America at around 250 million years. Interesting to watch. All of the Earth’s eras, seen on the web images, are linked to information on them. I think the best way to use this site in an introductory lesson would be for the students to explore it for 15 to 20 minutes with a KWL chart, followed by a discussion of the things they wrote down in the Learn column.